U.S. patent number 9,081,282 [Application Number 14/187,423] was granted by the patent office on 2015-07-14 for pattern formation using electroless plating and articles.
This patent grant is currently assigned to EASTMAN KODAK COMPANY. The grantee listed for this patent is Thomas B. Brust, Catherine A. Falkner, Mark Edward Irving. Invention is credited to Thomas B. Brust, Catherine A. Falkner, Mark Edward Irving.
United States Patent |
9,081,282 |
Brust , et al. |
July 14, 2015 |
Pattern formation using electroless plating and articles
Abstract
A conductive pattern can be formed using a polymeric layer that
contains a reactive composition that comprises a reactive polymer
that is metal ion-complexing, water-soluble, and crosslinkable.
This reactive polymer comprises pendant groups comprising
crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R
and R.sup.1 are defined in the disclosure, as well as metal
ion-complexing and water solubilizing groups. The reactive
composition can be patternwise exposed to suitable radiation to
induce crosslinking within the reactive polymer. The reactive
composition and reactive polymer in the non-exposed regions can be
removed due to their aqueous solubility, but the exposed regions of
the polymeric layer are contacted with electroless seed metal ions,
which are then reduced. The resulting electroless seed metal nuclei
are electrolessly plated with a suitable metal to form the desired
conductive pattern. Various articles can be prepared during this
process, and the product article can be incorporated into various
electronic devices.
Inventors: |
Brust; Thomas B. (Webster,
NY), Falkner; Catherine A. (Rochester, NY), Irving; Mark
Edward (Rochester, NY) |
Applicant: |
Name |
City |
State |
Country |
Type |
Brust; Thomas B.
Falkner; Catherine A.
Irving; Mark Edward |
Webster
Rochester
Rochester |
NY
NY
NY |
US
US
US |
|
|
Assignee: |
EASTMAN KODAK COMPANY
(Rochester, NY)
|
Family
ID: |
53506729 |
Appl.
No.: |
14/187,423 |
Filed: |
February 24, 2014 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03F
7/0388 (20130101); G03F 7/405 (20130101); G03F
7/00 (20130101); G03F 7/40 (20130101) |
Current International
Class: |
G03F
7/26 (20060101); G03F 7/16 (20060101); G03F
7/20 (20060101); G03F 7/038 (20060101) |
Field of
Search: |
;430/270.1,311,322 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
L M. Minsk, et al., "Photosensitive Polymers. I. Cinnamate Esters
of Poly(vinyl Alcohol) and Cellulose," Journal of Applied Polymer
Science, vol. II, Issue No. 6, pp. 302-307 (1959). cited by
applicant.
|
Primary Examiner: Sullivan; Caleen
Attorney, Agent or Firm: Tucker; J. Lanny
Claims
The invention claimed is:
1. A method for forming a pattern in a polymeric layer, the method
comprising: providing a polymeric layer comprising a reactive
composition that comprises: (1) a reactive polymer that is metal
ion-complexing, water-soluble, and crosslinkable, which reactive
polymer comprises a backbone, and arranged in any order along the
backbone, --A--recurring units that comprise pendant groups
comprising crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups
wherein R and R.sup.1 are independently hydrogen or an alkyl group
having 1 to 7 carbon atoms, a 5- to 6-membered cycloalkyl group, an
alkoxy group having 1 to 7 carbon atoms, a phenyl group, or a
phenoxy group, and Y is a substituted or unsubstituted aryl or
aromatic heterocyclic ring, in an amount of at least 2 mol %, and
--B-- recurring units comprising pendant metal ion-complexing and
water-solubilizing groups in an amount of at least 50 mol %, both
based on the total recurring units in the reactive polymer; and (2)
optionally, a photosensitizer, patternwise exposing the polymeric
layer to radiation having a .lamda..sub.max of at least 150 nm that
is sufficient to induce crosslinking within the reactive polymer,
to provide a polymeric layer comprising non-exposed regions and
exposed regions comprising an at least partially crosslinked
polymer derived from the reactive polymer, optionally heating the
polymeric layer simultaneously with or after patternwise exposing
the polymeric layer but before removing the reactive composition
comprising the reactive polymer in the non-exposed regions, at a
temperature sufficient to further crosslink the at least partially
crosslinked polymer in the exposed regions of the polymeric layer,
removing the reactive composition comprising the reactive polymer
in the non-exposed regions, contacting the exposed regions of the
polymeric layer with electroless seed metal ions to form a pattern
of electroless seed metal ions in the exposed regions of the
polymeric layer, reducing the pattern of electroless seed metal
ions to provide a pattern of corresponding electroless seed metal
nuclei in the exposed regions of the polymeric layer, and
electrolessly plating the corresponding electroless seed metal
nuclei in the exposed regions of the polymeric layer with a metal
that is the same as or different from the corresponding electroless
seed metal nuclei.
2. The method of claim 1, wherein the --A-- recurring units are
present in an amount of at least 2 mol % and up to and including 50
mol %, and the --B-- recurring units are present in an amount of at
least 50 mol % and up to and including 98 mol %, both based on the
total recurring units in the reactive polymer.
3. The method of claim 1, wherein the --B-- recurring units
comprise pendant carboxylic acid, carboxylate, sulfonic acid, or
sulfonate groups.
4. The method of claim 1, wherein the reactive polymer comprises at
least 10 mol % and up to and including 40 mol % of --A-- recurring
units comprising crosslinkable --C(.dbd.O)--CR--CR.sup.1-phenyl
groups wherein R and R.sup.1 are independent hydrogen, methyl,
ethyl, or phenyl groups, based on the total recurring units in the
reactive polymer, and at least 60 mol % and up to and including 90
mol % of --B-- recurring units.
5. The method of claim 1, wherein the reactive polymer further
comprises one or more additional --C-- recurring units that are
different from all --A-- and --B-- recurring units, the one or more
additional --C-- recurring units being present in an amount of up
to and including 20 mol % based on the total reactive polymer
recurring units.
6. The method of claim 1, wherein the reactive polymer comprises at
least 50 weight % and up to 100 weight % of the total dry weight of
the polymeric layer.
7. The method of claim 1, wherein the reactive composition further
comprises a photosensitizer in the polymeric layer in an amount of
at least 0.1 weight % based on the total solids in the polymeric
layer, which photosensitizer provides sensitization at a
.lamda..sub.max of at least 150 nm and up to and including 700
nm.
8. The method of claim 1, further comprising: heating the polymeric
layer after patternwise exposing the polymeric layer but before
removing the reactive composition comprising the reactive polymer
in the non-exposed regions, at a temperature sufficient to further
crosslink the at least partially crosslinked polymer in the exposed
regions of the polymeric layer.
9. The method of claim 1, comprising contacting the exposed regions
in the polymeric layer with electroless seed metal ions selected
from the groups consisting of silver ions, platinum ions, palladium
ions, gold ions, rhodium ions, nickel ions, iridium ions, tin ions,
and copper ions.
10. The method of claim 1, comprising electrolessly plating with a
metal that is selected from the group consisting of copper(II),
silver(I), gold(IV), palladium(II), platinum(II), nickel(II),
chromium(II), and combinations thereof.
11. The method of claim 1, comprising patternwise exposing the
polymeric layer to radiation having a .lamda..sub.max of at least
150 nm and up to and including 450 nm.
12. The method of claim 1, comprising reducing the electroless seed
metal ions in the exposed regions of the polymeric layer with a
reducing agent that is a borane, aldehyde, hydroquinone, or sugar
reducing agent.
13. A precursor article used in the method of claim 1, the
precursor article comprising a substrate and having disposed
thereon a polymeric layer comprising a reactive composition that
comprises: (1) a reactive polymer that is metal ion-complexing,
water-soluble, and crosslinkable, which reactive polymer comprises
a backbone, and arranged in any order along the backbone, --A--
recurring units that comprise pendant groups comprising
crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R
and R.sup.1 are independently hydrogen or an alkyl group having 1
to 6 carbon atoms, a 5- to 6-membered cycloalkyl group, an alkoxy
group having 1 to 6 carbon atoms, a phenyl group, or a phenoxy
group, and Y is a substituted or unsubstituted aryl or aromatic
heterocyclic ring, in an amount of at least 2 mol %; and --B--
recurring units comprising pendant metal ion-complexing and
water-solubilizing groups in an amount of at least 50 mol %, both
based on the total recurring units in the reactive polymer, and (2)
optionally, a photosensitizer.
14. The precursor article of claim 13, wherein the --A-- recurring
units are present in an amount of at least 2 mol % and up to and
including 50 mol %, and the --B-- recurring units are present in an
amount of at least 50 mol % and up to and including 98 mol %, both
based on the total recurring units in the reactive polymer.
15. The precursor article of claim 13, wherein the --B-- recurring
units comprise pendant carboxylic acid, carboxylate, sulfonic acid,
or sulfonate groups.
16. The precursor article of claim 13, wherein the reactive polymer
comprises at least 10 mol % and up to and including 40 mol % of
--A-- recurring units comprising crosslinkable
--C(.dbd.O)--CR.dbd.CR.sup.1-phenyl groups wherein R and R.sup.1
are independent hydrogen, methyl, ethyl, or phenyl groups, based on
the total recurring units in the reactive polymer, and at least 60
mol % and up to and including 90 mol % of --B-- recurring
units.
17. The precursor article of claim 13, wherein the reactive polymer
further comprises one or more additional --C-- recurring units that
are different from all --A-- and --B-- recurring units, the one or
more additional --C-- recurring units being present in an amount of
up to and including 20 mol % based on the total reactive polymer
recurring units.
18. The precursor article of claim 13, wherein the reactive
composition further comprises a photosensitizer in the polymeric
layer in an amount of at least 0.1 weight % based on the total
solids in the polymeric layer, which photosensitizer provides
sensitization at a .lamda..sub.max of at least 150 nm and up to and
including 700 nm.
19. A product article prepared by the method of claim 1, the
product article comprising a substrate and having disposed thereon
a polymeric layer comprising exposed regions and non-exposed
regions, the exposed regions comprising a pattern of electrolessly
plated metal complexed within or deposited on the surface of an at
least partially crosslinked polymer that has been derived from a
reactive polymer that is metal ion-complexing, water-soluble, and
crosslinkable, which reactive polymer comprises a backbone, and
arranged in any order along the backbone, --A-- recurring units
that comprise pendant groups comprising crosslinkable
--C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R and R.sup.1 are
independently hydrogen or an alkyl group having 1 to 7 carbon
atoms, a 5- to 6-membered cycloalkyl group, an alkoxy group having
1 to 7 carbon atoms, a phenyl group, or a phenoxy group, and Y is a
substituted or unsubstituted aryl or aromatic heterocyclic ring, in
an amount of at least 2 mol %, and --B-- recurring units comprising
pendant metal ion-complexing and water-solubilizing groups in an
amount of at least 50 mol %, both based on the total recurring
units in the reactive polymer, and the non-exposed regions
comprising none of the electrolessly plated metal or the reactive
polymer that is metal ion-complexing, water-soluble, and
crosslinkable.
Description
FIELD OF THE INVENTION
This invention relates to methods for forming patterns of a
reactive polymer that can be used for forming other material
patterns such as conductive metallic patterns, for example using
electroless plating. The invention is carried out using
water-soluble, cinnamoyl-containing crosslinkable reactive polymers
that can be crosslinked upon suitable irradiation. This invention
also relates to precursor, intermediate, and product articles
related to the inventive method.
BACKGROUND OF THE INVENTION
In recent decades accompanying rapid advances in
information-oriented society, there have also been rapid
technological advances to provide devices and systems for gathering
and communicating information. Of these, display devices have been
designed for television screens, commercial signage, personal and
laptop computers, personal display devices, and phones of all
types, to name the most common information sharing devices.
As the increase in the use of such devices has exploded in
frequency and necessity by displacing older technologies, there has
been a concern that electromagnetic radiation emission from such
devices may cause harm to the human body or neighboring devices or
instruments over time. To diminish the potential effects from the
electromagnetic radiation emission, display devices are designed
with various transparent conductive materials that can be used as
electromagnetic wave shielding materials.
In display devices where a continuous conductive film is not
practical for providing this protection from electromagnetic
radiation emission, it has been found that conductive mesh or
patterns can be used for this electromagnetic wave shielding
purpose for example as described in U.S. Pat. No. 7,934,966 (Sasaki
et al.).
Other technologies have been developed to provide new
microfabrication methods to provide metallic, two-dimensional, and
three-dimensional structures with conductive metals. Patterns have
been provided for these purposes using photolithography and imaging
through mask materials as described for example in U.S. Pat. No.
7,399,579 (Deng et al.).
In addition, as the noted display devices have been developed in
recent years, attraction has increased greatly for the use of touch
screen technology whereby a light touch on a transparent screen
surface with a finger or stylus can create signals to cause changes
in screen views or cause the reception or sending of information,
telecommunications, interaction with the internet, and many other
features that are being developed at an ever-increasing pace of
innovation. The touch screen technology has been made possible
largely by the use of transparent conductive grids on the primary
display so that the location of the noted touch on the screen
surface can be detected by appropriate electrical circuitry and
software.
For a number of years, touch screen displays have been prepared
using indium tin oxide (ITO) coatings to create arrays of
capacitive patterns or areas used to distinguish multiple point
contacts. ITO can be readily patterned using known semiconductor
fabrication methods including photolithography and high vacuum
processing. However, the use of ITO coatings has a number of
disadvantages. Indium is an expensive rare earth metal and is
available in limited supply. Moreover, ITO is a ceramic material
and is not easily bent or flexed and such coatings require
expensive vacuum deposition methods and equipment. In addition, ITO
conductivity is relatively low, requiring short line lengths to
achieve desired response rates (upon touch). Touch screens used in
large displays are broken up into smaller segments in order to
reduce the conductive line length to provide acceptable electrical
resistance. These smaller segments require additional driving and
sensing electronics, further adding to the cost of the devices.
Silver is an ideal conductor having conductivity that is 50 to 100
times greater than that of ITO. Unlike most metal oxides, silver
oxide is still reasonably conductive and its use reduces the
problem of making reliable electrical connections. Moreover, silver
is used in many commercial applications and is available from
numerous commercial sources.
In other technologies, transparent polymeric films have been
treated with conductive metals such as silver, copper, nickel, and
aluminum by such methods as sputtering, ion plating, ion beam
assist, wet coating, as well as the vacuum deposition. However, all
of these technologies are expensive, tedious, or extremely
complicated so that the relevant industries are spending
considerable resources to design improved means for forming
conductive patterns for various devices especially touch screen
displays.
A similar level of transparency and conductivity for patterns can
be achieved by producing very fine lines of about 5-6 .mu.m in
width of highly conductive material such as copper or silver metal
or conductive polymers.
Crosslinkable polymers having cinnamate functionality have been
described for use in photoresists for example, by Minsk et al. in
the J. Appl. Polym. Sci. 1959, 2, 302-307. In general, such
polymers have been formulated in organic solvents for application
to suitable substrates.
U.S. Pat. No. 3,799,915 (Dunnavant et al.) describes photosensitive
polymers derived from cinnamoyl acrylate esters and various
co-monomers for use in preparing lithographic printing plates.
While a variety of polymers have been developed for providing
conductive patterns using electroless plating methods, such
polymers are generally insoluble in water and must be coated out of
expensive and sometimes toxic organic solvents.
There is a need for a way to make reactive polymer patterns that
can be used for producing thin conductive lines using less
expensive materials and plating techniques in order to achieve a
substantial improvement in cost, reliability, and availability of
conductive patterns for various display devices. It is desirable to
achieve these results using aqueous formulations instead of organic
solvent coating formulations. The present invention addresses this
need as described in considerable detail below.
SUMMARY OF THE INVENTION
The present invention provides a method for using the reactive
polymers described herein to address some of the noted
problems.
Thus, the present invention provides a method for forming a pattern
in a polymeric layer, the method comprising:
providing a polymeric layer comprising a reactive composition that
comprises: (1) a reactive polymer that is metal ion-complexing,
water-soluble, and crosslinkable, which reactive polymer comprises
pendant groups comprising crosslinkable
--C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R and R.sup.1 are
independently hydrogen or an alkyl group having 1 to 6 carbon
atoms, a 5- to 6-membered cycloalkyl group, an alkoxy group having
1 to 6 carbon atoms, a phenyl group, or a phenoxy group, and Y
represents a substituted or unsubstituted aryl or aromatic
heterocyclic ring and (2) optionally, a photosensitizer,
patternwise exposing the polymeric layer to radiation having a
.lamda..sub.max of at least 150 nm that is sufficient to induce
crosslinking within the reactive polymer, to provide a polymeric
layer comprising non-exposed regions and exposed regions comprising
an at least partially crosslinked polymer derived from the reactive
polymer,
optionally heating the polymeric layer simultaneously with or after
patternwise exposing the polymeric layer but before removing the
reactive composition comprising the reactive polymer in the
non-exposed regions, at a temperature sufficient to further
crosslink the at least partially crosslinked polymer in the exposed
regions of the polymeric layer,
removing the reactive composition comprising the reactive polymer
in the non-exposed regions,
contacting the exposed regions of the polymeric layer with
electroless seed metal ions to form a pattern of electroless seed
metal ions in the exposed regions of the polymeric layer,
reducing the pattern of electroless seed metal ions to provide a
pattern of corresponding electroless seed metal nuclei in the
exposed regions of the polymeric layer, and
electrolessly plating the corresponding electroless seed metal
nuclei in the exposed regions of the polymeric layer with a metal
that is the same as or different from the corresponding electroless
seed metal nuclei.
The present invention also provides a precursor article that can be
used in the method of this invention, the precursor article
comprising a substrate and having disposed thereon a polymeric
layer comprising a reactive composition that comprises:
(1) a reactive polymer that is metal ion-complexing, water-soluble,
and crosslinkable, which reactive polymer comprises pendant groups
comprising crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups
wherein R, R.sup.1, and Y are as described below, and (2)
optionally, a photosensitizer.
An intermediate article provided during the practice of the present
invention, comprises a substrate and having disposed thereon a
polymeric layer comprising exposed regions and non-exposed
regions,
the exposed regions comprising a pattern of at least partially
crosslinked polymer that has been derived from a reactive polymer
that is metal ion-complexing, water-soluble, and crosslinkable,
which reactive polymer comprises pendant groups comprising
crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R,
R.sup.1, and Y are as described below, and
the non-exposed regions comprising a reactive composition that
comprises the reactive polymer that is metal ion-complexing,
water-soluble, and crosslinkable, and optionally, a
photosensitizer.
Further, another intermediate article provided in the practice of
this invention comprises a substrate and having disposed thereon a
polymeric layer comprising exposed regions and non-exposed
regions,
the exposed regions comprising a pattern of at least partially
crosslinked polymer that has been derived from a reactive polymer
that is metal ion-complexing, water-soluble, and crosslinkable,
which reactive polymer comprises pendant groups comprising
crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R,
R.sup.1, and Y are as described below, and
the non-exposed regions comprising none of the reactive polymer
that is metal ion-complexing, water-soluble, and crosslinkable.
In addition, another intermediate article that is provided in the
practice of this invention comprises a substrate and having
disposed thereon a polymeric layer comprising exposed regions and
non-exposed regions,
the exposed regions comprising a pattern of electroless seed metal
ions complexed within an at least partially crosslinked polymer
that has been derived from a reactive polymer that is metal
ion-complexing, water-soluble, and crosslinkable, which reactive
polymer comprises pendant groups comprising crosslinkable
--C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R, R.sup.1, and Y
are as described below, and
the non-exposed regions comprising none of the electroless seed
metal ions or the reactive polymer that is metal ion-complexing,
water-soluble, and crosslinkable.
Still again, an intermediate article provided during the practice
of this invention comprises a substrate and having disposed thereon
a polymeric layer comprising exposed regions and non-exposed
regions,
the exposed regions comprising a pattern of electroless seed metal
nuclei complexed within an at least partially crosslinked polymer
that has been derived from a reactive polymer that is metal
ion-complexing, water-soluble, and crosslinkable, which reactive
polymer comprises pendant groups comprising crosslinkable
--C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R, R.sup.1, and Y
are as described below, and
the non-exposed regions comprising none of the electroless seed
metal nuclei or the reactive polymer that is metal ion-complexing,
water-soluble, and crosslinkable.
A product article obtained from the method of this invention
comprises a substrate and having disposed thereon a polymeric layer
comprising exposed regions and non-exposed regions,
the exposed regions comprising a pattern of electrolessly plated
metal complexed within or deposited on the surface of an at least
partially crosslinked polymer that has been derived from a reactive
polymer that is metal ion-complexing, water-soluble, and
crosslinkable, which reactive polymer comprises pendant groups
comprising crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups
wherein R, R.sup.1, and Y are as described below, and
the non-exposed regions comprising none of the electrolessly plated
metal or the reactive polymer that is metal ion-complexing,
water-soluble, and crosslinkable.
The present invention provides an efficient method for forming
conductive metal patterns using a specifically designed reactive
polymer that can be coated out of an aqueous formulation and
crosslinked during appropriate irradiation (UV or visible light).
The reactive polymer can undergo crosslinking reactions including
but not limited to a photocycloaddition reaction, through adjacent
or proximate cinnamoyl or cinnamoyl-like groups upon irradiation
and the incorporated water-solubilizing groups can also provide
electroless seed metal ion-complexation sites. Because of the
crosslinking function of the reactive polymer, additional
crosslinking agents in the reactive composition are
unnecessary.
Crosslinking with the reactive polymer crosslinking provides
water-insoluble metal ion complexation sites in the exposed regions
of a polymeric layer while leaving the non-exposed regions
water-soluble so the reactive polymer can be removed before
conductive metal patterns are formed in the exposed regions. The
water-solubility of the reactive polymer is provided generally by
the incorporation of suitable amounts of pendant water-solubilizing
groups along the reactive polymer backbone. Thus, the reactive
polymer has two essential functions and components: (1) pendant
crosslinkable groups described herein, and (2) pendant reactive and
water-solubilizing groups. Both of these groups are incorporated
into the reactive polymer in desirable proportions.
The present invention avoids the use of expensive high vacuum
processes necessary for making conductive patterns using indium tin
oxide (ITO) coatings and is more readily carried out using
high-speed roll-to-roll machines for higher manufacturing
efficiencies.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
As used herein to define various ethylenically unsaturated
polymerizable monomer components (or recurring units) of the
reactive polymers, solutions, reactive compositions, aqueous-based
solutions, and polymeric layers, unless otherwise indicated, the
singular forms "a", "an", and "the" are intended to include one or
more of the components (that is, including plurality
referents).
Each term that is not explicitly defined in the present application
is to be understood to have a meaning that is commonly accepted by
those skilled in the art. If the construction of a term would
render it meaningless or essentially meaningless in its context,
the term definition should be taken from a standard dictionary.
The use of numerical values in the various ranges specified herein,
unless otherwise expressly indicated, are considered to be
approximations as though the minimum and maximum values within the
stated ranges were both preceded by the word "about". In this
manner, slight variations above and below the stated ranges can be
used to achieve substantially the same results as the values within
the ranges. In addition, the disclosure of these ranges is intended
as a continuous range including every value between the minimum and
maximum values.
Unless otherwise indicated, the term "weight %" refers to the
amount of a component or material based on the total solids of a
composition, formulation, or layer. Unless otherwise indicated, the
percentages can be the same for either a dry layer or pattern, or
for the total solids of the formulation or composition.
The term "homopolymer" is meant to refer to polymeric materials
that have the same repeating or recurring unit along a polymer
backbone. The term "copolymer" refers to polymeric materials
composed of two or more different repeating or recurring units that
are arranged randomly along the polymer backbone.
The recurring units in the reactive polymers used in this invention
are not intentionally incorporated into the reactive polymers in
block arrangements, but the recurring units can be incorporated
into the backbone in any fashion using known polymerization
procedures. The reactive polymers can be entirely random in the
arrangement of recurring units, or there can be blocks of one or
more different recurring units arranged along the polymer chain, or
there can be both random and block arrangements of recurring units
along the same polymer chain.
Recurring units in reactive polymers described herein are generally
derived from the corresponding ethylenically unsaturated
polymerizable monomers used in a polymerization process, which
ethylenically unsaturated polymerizable monomers have the desired
functional and pendant groups. Alternatively, pendant groups can be
incorporated within recurring units after polymerization of
ethylenically unsaturated polymerizable monomers by reaction with
requisite precursor pending groups.
The term "reactive polymer" is used herein to refer to the polymers
described below that have the essential components and properties
described and can be used in the method of the present
invention.
By "solubility or dispersibility" in reference to the reactive
polymer, we mean that a uniform stable solution or dispersion of
reactive polymer can be prepared using a desired solvent at a
solids concentration that is useful for use in the present
invention, for example preparation of coating formulations.
The term "aqueous-based" refers to solutions, baths, or dispersions
in which the predominant solvent, or at least 50 weight % of the
solvents, is water.
Unless otherwise indicated, the term "mol %" when used in reference
to recurring units in reactive polymers, refers to either the
nominal (theoretical) amount of a recurring unit based on the
molecular weight of ethylenically unsaturated polymerizable monomer
used in the polymerization process, or to the actual amount of
recurring unit in the resulting reactive polymer as determined
using suitable analytical techniques and equipment.
Uses
The methods of this invention can be used to provide reactive
polymer patterns that can be used to form conductive metal patterns
as described herein, which conductive metal patterns can be
incorporated into various devices including but not limited to
touch screen or other display devices.
For example, the reactive compositions described herein can be used
for a variety of purposes where efficient photopolymerization and
metal pattern formation is needed in various articles or devices.
Such reactive compositions must be sensitive to a chosen radiation
wavelength as noted above. For example, the reactive compositions
can be used in various methods that can provide conductive metal
patterns, for example using electroless plating procedures, which
conductive metal patterns can be incorporated into various devices
including but not limited to touch screen or other display devices
that can be used in numerous industrial, consumer, and commercial
products.
For example, touch screen technology can comprise different touch
sensor configurations including capacitive and resistive touch
sensors. Resistive touch sensors comprise several layers that face
each other with a gap between adjacent layers that may be preserved
by spacers formed during manufacturing. A resistive touch screen
panel can comprise several layers including two thin, metallic,
electrically conductive layers separated by a gap that can be
created by spacers. When a object such as a stylus, palm, or finger
presses down on a point on the panel's outer surface, the two
metallic layers come into contact and a connection is formed that
causes a change in the electrical current. This touch event is sent
to a controller for further processing.
Capacitive touch sensors can be used in electronic devices with
touch-sensitive features. These electronic devices can include but
are not limited to, televisions, monitors, and projectors that can
be adapted to display images including text, graphics, video
images, movies, still images, and presentations. The image devices
that can be used for these display devices that can include cathode
ray tubes (CRS's), projectors, flat panel liquid crystal displays
(LCD's), LED systems, OLED systems, plasma systems,
electroluminescent displays (ECD's), and field emission displays
(FED's). For example, the present invention can be used to prepare
capacitive touch sensors that can be incorporated into electronic
devices with touch-sensitive features to provide computing devices,
computer displays, portable media players including e-readers,
mobile telephones and other communicating devices.
Systems and methods of fabricating flexible and optically compliant
touch sensors in a high-volume roll-to-roll manufacturing process
where micro electrically conductive features can be created in a
single pass are possible using the present invention. The reactive
compositions can be used in such systems and methods with multiple
printing members to form multiple high resolution conductive images
from predetermined designs of patterns provided in those multiple
printing members. Multiple patterns can be printed on one or both
sides of a substrate. For example, one predetermined pattern can be
printed on one side of the substrate and a different predetermined
pattern can be printed on the opposing side of the substrate. The
printed patterns of the photopolymerizable compositions can then be
further processed to provide conductive metal patterns using
electroless metal plating.
Reactive Polymers for Pattern Formation
In general, the reactive polymers useful in the practice of this
invention have two essential features: (1) they comprise
crosslinkable groups (defined below) that upon exposure to suitable
radiation can participate in crosslinking among adjacent (or
proximate) groups of the same type, and (2) reactive
water-solubilizing groups. While the reactive polymers can be
supplied as aqueous-based reactive compositions, they are best used
when applied to a substrate that can have a large or small surface,
including the outer surfaces of inorganic or organic particles and
then dried. Thus, the reactive polymers are metal ion-complexing
(as described below), water-soluble, and crosslinkable.
The reactive polymers can be either condensation or vinyl polymers
as long as the requisite crosslinkable and water-solubilizing
groups are connected to and arranged along the reactive polymer
backbone. In most embodiments, the useful reactive polymers are
vinyl polymers derived from ethylenically unsaturated polymerizable
monomers using solution or emulsion polymerization techniques and
conditions, initiators, surfactants, catalysts, and solvents, all
of which would be readily apparent to one skilled in the art from
the teaching provided herein.
The useful reactive polymers generally comprise at least some
recurring units arranged along the reactive polymer backbone that
comprise pendant crosslinkable groups comprising
--C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R, R.sup.1, and Y
are defined as follows.
Specifically, R and R.sup.1 are independently hydrogen or
substituted or unsubstituted alkyl groups having at least 1 to 7
carbon atoms (including substituted or unsubstituted methyl, ethyl,
isopropyl, t-butyl, hexyl, and benzyl groups, and others that would
be readily apparent to one skilled in the art), substituted or
unsubstituted cycloalkyl group having 5 or 6 carbon atoms in the
ring (such as cyclopentyl, cyclohexyl, 4-methylcyclohexyl, and
others that would be readily apparent to one skilled in the art),
substituted or unsubstituted phenyl groups (such as phenyl, tolyl,
and xylyl groups, and others that would be readily apparent to one
skilled in the art), substituted or unsubstituted alkoxy groups
having 1 to 7 carbon atoms (such as methoxy, ethoxy, benzoxy, and
others readily apparent to one skilled in the art), or substituted
or unsubstituted phenoxy groups (such as phenoxy,
2,4-dimethylphenoxy, and others that would be readily apparent to
one skilled in the art). In some embodiments, R and R.sup.1 can
also be nitro, cyano, or halogen groups.
The crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups can be
attached to the reactive polymer backbone in any suitable manner
through a suitable divalent group that is attached to either the
carbonyl moiety [--C(.dbd.O)--] or the --CR.sup.1--Y-- moiety of
the crosslinkable group. In either case, the divalent group can be
any of those that a skilled worker in the art would readily
understand as chemically possible, including the R.sup.2 groups
described below.
When the crosslinkable group is attached to the reactive polymer
backbone through a suitable divalent group that is attached to the
--Y-- moiety, the carbonyl moiety is usually attached to a
substituted or unsubstituted alkoxy or alkyl group having 1 to 10
carbon atoms (including benzyl groups) or to a substituted or
unsubstituted phenyl or naphthyl group. The carbonyl moiety can
also be a carboxylic acid or aldehyde.
In most embodiments, however, the crosslinkable group is defined by
--C(.dbd.O)--CR.dbd.CR.sup.1--Y-- wherein R and R.sup.1 are as
defined above and Y is defined below and the open valence shown for
"Y" is generally filled with a hydrogen atom, or an alkyl group as
described below for substituted Y groups. Such crosslinkable groups
then are attached to the reactive polymer backbone using a single
bond or a suitable divalent group that is attached to the carbonyl
moiety, for example those described by R.sup.2 below.
In most embodiments, when the crosslinkable group is attached to
the reactive polymer backbone through the carbonyl moiety, Y is a
substituted or unsubstituted carbocyclic aryl group, or a
substituted or unsubstituted heteroaryl group having one or more
heteroatoms (oxygen, sulfur, or nitrogen) and sufficient carbon
atoms to complete an aromatic heterocyclic ring. Such aromatic
rings can have one or more substituents that do not adversely
affect the desired behavior in the crosslinking reactions induced
by the irradiation described herein.
Useful Y groups can be either heterocyclic or carbocyclic rings
having desired aromaticity and any of these rings can be
substituted with one or more substituents that do not adversely
affect the function of the reactive polymer. Representative
aromatic Y groups include but are not limited to, substituted or
unsubstituted phenyl, naphthyl, anthracyl, 4-nitrophenyl,
2,4-dichlorophenyl, 4-ethylphenyl, tolyl, 4-dodecylphenyl,
2-nitro-3-chlorophenyl, 4-methoxyphenyl, 2-furyl, 2-thienyl,
3-indolyl, and 3-pyridyl rings. The substituted or unsubstituted
phenyl rings are particularly useful including but not limited to
phenyl, tolyl, xylyl, 4-methoxyphenyl, hydroxyphenyl, and
chlorophenyl groups. Substituted or unsubstituted phenyl or
3-pyridyl groups are particularly useful Y groups.
More particularly, R and R.sup.1 are independently hydrogen or
substituted or unsubstituted methyl, ethyl or phenyl groups,
especially when Y is a substituted or unsubstituted phenyl group as
described below.
Upon exposure to suitable radiation having a .lamda..sub.max of at
least 150 nm and up to and including 700 nm, or more likely exposed
to radiation having a .lamda..sub.max of at least 150 nm and up to
and including 450 nm, the noted crosslinkable
--C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups are electronically excited
such that they can react with other pendant groups in the reactive
polymer to form crosslinks for example as the product of
photocycloaddition reactions.
The reactive polymers particularly become crosslinked among
adjacent or proximate (molecularly near enough for example for
cycloaddition crosslinking) crosslinkable groups during or after
the noted irradiation. Thus, essential crosslinking can be
accomplished using the reactive polymer without additional
crosslinking agents. However, if desired, crosslinking can be
further provided using distinct compounds that are dispersed as
crosslinking agents within the polymeric layer (described below)
comprising one or more reactive polymers. Such crosslinking agents
react at either the crosslinkable groups or at the pendant water
solubilizing groups depending upon the chemical structure of
crosslinking agent. For the pendant crosslinkable groups described
above, crosslinking is achieved by having at least two of such
crosslinkable groups in proximity that can react with one another,
while incorporated aziridines or carbodiimides can react with
reactive water-solubilizing groups such as pendant carboxy
(carboxylic acid) groups.
Particularly useful reactive polymers can be represented by the
following essential --A--, --B--, and optional --C-- recurring
units in any order (random or otherwise) along the polymer
backbone.
In particular, the essential --A-- recurring units can be derived
from any ethylenically unsaturated polymerizable monomer having
appropriate pendant groups comprising one or more crosslinkable
--C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R, R.sup.1, and Y
are as defined above.
More particularly, the --A-- recurring units can be further defined
in reference to the following Structure (--A--) containing
crosslinkable groups:
##STR00001##
In this structure, R, R.sup.1, and Y are as defined above. R.sup.2
can be a divalent linking group including but are not limited to,
substituted or unsubstituted alkylene (including haloalkylenes and
cyanoalkylenes), alkyleneoxy, alkoxyalkylene, iminoalkylene,
cycloalkylene, aralkylene, cycloalkylene-alkylene, and
aryloxyalkylene groups wherein the divalent hydrocarbon groups can
comprise 1 to 20 carbon atoms (in either linear, branched, or
cyclic form). A skilled worker in polymer chemistry would be able
to design other useful linking groups using suitable number of
carbon and hetero (oxygen, nitrogen, or sulfur) atoms in an order
and arrangement that are chemically possible. Particularly useful
R.sup.2 divalent groups are substituted or unsubstituted alkylene
groups such as substituted or unsubstituted ethylene or
propylenes.
R.sup.3, R.sup.4, and R.sup.5 are independently hydrogen, a
halogen, a substituted or unsubstituted alkyl group having 1 to 6
carbon atoms, a substituted or unsubstituted cyclohexyl group, or a
substituted or unsubstituted phenyl group. In particular, R.sup.3,
R.sup.4, and R.sup.5 are independently hydrogen, chloro, methyl, or
ethyl groups.
Some particularly useful ethylenically unsaturated polymerizable
monomers from which --A-- recurring units can be derived include:
2-cinnamoyl-ethyl methacrylate, 2-cinnamoyl-ethyl acrylate,
2-[3-(3-pyridyl)acryloyl]ethyl methacrylate, 2-[ethyl
3-(4-oxyphenyl)acrylate]ethyl methacrylate, and 2-[ethyl
3-(4-carbonyloxyphenyl)acrylate]ethyl methacrylate.
The --A-- recurring units can also be formed after formation of a
reactive polymer having precursor --A-- recurring units. For
example, a polymer can be prepared with recurring units derived
from vinyl alcohols or acrylate monomers having pendant hydroxyl
groups, and the pendant hydroxyl groups can be reacted with
cinnamoyl chloride (or similar substituted cinnamoyl-like chloride
reactants) to form the desired --A-- recurring units with pendant
water-solubilizing groups already within the polymer before the
reaction to form the --A-- recurring units.
Useful essential --B-- recurring units within the reactive polymer
can be derived from any ethylenically unsaturated polymerizable
monomer that comprises pendant water-solubilizing groups, or
pendant precursor groups that can be converted to
water-solubilizing groups after polymerization. Such pendant
water-solubilizing groups are also generally metal ion-complexing
(or metal ion-reactive) and include but are not limited to,
carboxylic acid, sulfonic acid, and phosphonic acid groups as well
as neutralized salts of these acid groups (such as carboxylate and
sulfonate groups). The sulfonic acid, sulfonate, carboxylic acid,
and carboxylate groups are particularly useful. Other useful
pendant water-solubilizing groups would be readily apparent to one
skilled in the art. Useful pendant precursor groups include but are
not limited to, anhydrides, esters (such as tertiary alkyl esters),
alcohols, and benzyl groups such as iminobenzyl sulfonates and
nitrobenzyl sulfonates.
For example, the essential --B-- recurring units can be represented
by the following Structure (--B--):
##STR00002## wherein B' represents a pendant group comprising the
desired water-solubilizing group (noted above) or precursor groups,
which group can be directly attached to the reactive polymer
backbone or it can be attached through a suitable divalent linking
group.
For example, some useful ethylenically unsaturated polymerizable
monomers from which the --B-- recurring units can be derived
include but are not limited to, acrylic acid, methacrylic acid,
styrene sulfonic acid, itaconic acid, maleic anhydride, fumaric
acid, citraconic acid, vinyl benzoic acid, 2-carboxyethyl acrylate,
2-carboxyethyl methacrylate, 2-acrylamido-2-methyl-1-propane
sulfonic acid, 2-sulfoethyl methacrylate, styrene sulfonates, and
styrene sulfonic acid. Partially or fully neutralized counterparts
of these monomers are also useful.
In addition to the --A-- and --B-- recurring units described above
that are essential in useful reactive polymers, the reactive
polymers can further comprise one or more additional recurring
units that are different from all --A-- and --B-- recurring units,
and herein identified as optional --C-- recurring units. A skilled
polymer chemist would understand how to choose such additional
recurring units, and for example, they can be derived from one or
more ethylenically unsaturated polymerizable monomers selected from
the group consisting of alkyl acrylates, alkyl methacrylates,
(meth)acrylamides, styrene and styrene derivatives, vinyl ethers,
vinyl benzoates, vinylidene halides, vinyl halides, vinyl imides,
and other materials that a skilled worker in the art would
understand could provide desirable properties to the reactive
polymer. Such --C-- recurring units can be represented by the
following Structure (--C--):
##STR00003## wherein the D groups in the --C-- recurring units can
be for example, hydrogen, substituted or unsubstituted alkyl groups
(such as hydroxyalkyl groups), substituted or unsubstituted aryl
groups (such as substituted or unsubstituted phenyl groups
including those found in styrenes), alkyl ester groups, aryl ester
groups, halogens, or ether groups. In many useful --C-- recurring
units, the D groups are alkyl carboxyl ester groups wherein the
alkyl moiety has 1 to 6 carbon atoms and is linear, branched, or
cyclic in form.
In addition, some --C-- recurring units can comprise an epoxy (such
as a glycidyl group) or epithiopropyl group derived for example
from glycidyl methacrylate or glycidyl acrylate.
In the --B-- and --C-- recurring units in the noted Structures, R,
R', and R'' can be the same or different hydrogen, methyl, ethyl,
or chloro groups and each type of recurring unit can have the same
or different R, R', and R'' groups along the polymer backbone. In
most embodiments, R, R', and R'' are hydrogen or methyl, and R, R',
and R'' can be the same or different for the various --B--, and
--C-- recurring units in a given reactive polymer. In addition, the
R, R', and R'' groups in the --B-- and --C-- recurring units can be
the same or different as the R.sup.3, R.sup.4, and R.sup.5 groups
in the --A-- recurring units.
In some embodiments, the reactive polymer comprises a backbone and
arranged along the backbone:
--A-- recurring units comprising pendant groups comprising the
crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R,
R.sup.1, and Y are defined above, and
--B-- recurring units comprising pendant metal ion-reactive and
water-solubilizing groups,
wherein the --A-- recurring units are present in an amount of at
least 2 mol % and up to and including 50 mol %, and the --B--
recurring units are present in an amount of at least 50 mol % and
up to and including 98 mol %, both based on the total recurring
units in the reactive polymer.
In particular, some --B-- recurring units comprise carboxylic acid,
carboxylate, sulfonic acid, or sulfonate groups, or a mixture of
such pendant groups in randomly occurring recurring units along the
reactive polymer backbone.
For example, the reactive polymer can comprise at least 2 mol % and
up to and including 50 mol % of --A-- recurring units comprising
crosslinkable --C(.dbd.O)--CH.dbd.CH-phenyl groups, based on the
total recurring units in the reactive polymer, wherein the phenyl
groups are substituted or unsubstituted as described above for the
aryl Y groups.
In addition, such reactive polymers can further comprise one or
more additional --C-- recurring units that are different from all
--A-- and --B-- recurring units, the one or more additional --C--
recurring units being present in an amount of up to and including
50 mol % based on the total reactive polymer recurring units.
In the --A--, --B--, and --C-- recurring unit formulae shown above,
"m", "n", and "p" are used to represent the respective molar
amounts of recurring units, based on total recurring units, in a
given reactive polymer, so that the sum of m, n, and p equal 100
mol % in a given reactive polymer. However, it is to be understood
that "m" and "n" do not only refer to the amounts of the --A-- and
--B-- recurring units, but to all recurring units in the reactive
polymer that provide the desired functionalities (crosslinking and
water-solubility) as described above.
In general, m is at least 2 mol %, or even at least 5 mol % and up
to and including 50 mol %, or at least 10 mol % and up to and
including 40 mol %, based on the total recurring units in the
reactive polymer. In addition, n generally represents at least 50
mol % and up to and including 98 mol %, or more typically at least
60 mol % and up to and including 95 mol %, or even at least 70 mol
% and up to and including 90 mol %, based on the total recurring
units in the reactive polymer.
Moreover, while p can be 0 mol %, it also can be up to and
including 50 mol %, or typically at least 1 mol % and up to and
including 20 mol %, or at least 2 mol % and up to and including 10
mol %, based on the total recurring units in the reactive
polymer.
The mol % amounts of the various recurring units defined herein for
the reactive polymers defined herein are meant to refer to the
actual molar amounts present in the reactive polymers. It is
understood by one skilled in the art that the actual mol % values
may differ from those theoretically possible from the amount of
ethylenically unsaturated polymerizable monomers that are used in
the polymerization procedure. However, under most polymerization
conditions that allow high polymer yield and optimal reaction of
all monomers, the actual mol % of each monomer is generally within
+15 mol % of the theoretical amounts.
Some representative reactive polymer embodiments include but are
not limited to, the following copolymers and terpolymers wherein
the molar ratios are theoretical (nominal) amounts based on the
actual molar ratio of ethylenically unsaturated polymerizable
monomers used in the polymerization process. The actual molar
amounts of recurring units can differ from the theoretical
(nominal) amounts of monomers if the polymerization reactions are
not carried out to completion. Poly(methacrylic
acid-co-2-cinnamoylethyl methacrylate) (90:10); Poly(acrylic
acid-co-2-cinnamoylethyl methacrylate) (80:20); Poly(acrylic
acid-co-2-cinnamoylethyl methacrylate) (70:30); Poly(acrylic
acid-co-2-cinnamoylethyl methacrylate) (60:40); Poly(acrylic
acid-co-2-cinnamoylethyl methacrylate) (50:50);
Poly(2-acrylamindo-2-methyl-1propanesulfonic
acid-co-2-cinnamoylethyl methacrylate (80:20); Poly(2-carboxyethyl
methacrylate-co-2-cinnamoylethyl methacrylate (80:20);
Poly(2-sulfoethyl methacrylate-co-2-cinnamoylethyl methacrylate
(80:20); Poly(styrene sulfonic acid-co-2-cinnamoylethyl
methacrylate) (80:20); and Poly(methacrylic
acid-co-2-[3-(3-pyridyl)acryloyl]ethyl methacrylate) (80:20),
Poly(methacrylic acid-co-[ethyl 3-(4-oxyphenyl)acrylate]ethyl
methacrylate) (80:20), and Poly[methacrylic acid-co-2-[ethyl
3-(4-carbonyloxyphenyl)-acrylate]ethyl methacrylate) (80:20).
The reactive polymers useful in the invention generally have a
molecular weight (M.sub.w) of at least 30,000 and up to and
including 300,000 as measured by gel permeation chromatography
(GPC) or by size exclusion chromatography (SEC).
Examples of reactive polymers can be prepared using known free
radical solution polymerization techniques using known starting
materials, free radical initiators, and reaction conditions in
suitable organic solvents such as tetrahydrofuran that can be
adapted from known polymer chemistry. Where starting materials
(such as ethylenically unsaturated polymerizable monomers) are not
available commercially, such starting materials can be synthesized
using known chemical starting materials and procedures.
Representative preparations of particularly useful reactive
polymers are provided below for the Invention Examples. Additional
details of polymerization procedures and starting materials can be
found in U.S. Pat. No. 3,799,915 (noted above), the disclosure of
such details being incorporated herein by reference. For example,
once the reactive polymer is prepared in a suitable organic
reaction solvent, it can be extracted into water by partial or
complete neutralization of the water-solubilizing groups to render
the reactive polymer highly water soluble. This aqueous solution of
the neutralized reactive polymer can be diluted or concentrated as
desired for application to a substrate, and is generally present at
a concentration of less than 20 weight %.
In general, the reactive polymers can be stored in solution in
suitable aqueous solutions or dispersions. Depending upon the
sensitivity of the reactive polymer to light (such as room light),
during and after preparation, the reactive polymers can be kept in
the dark or away from light exposure until they are formulated into
reactive compositions and used for various purposes. To enhance
storage stability, one or more acid scavengers, such as hindered
amines, can be added to the reactive polymer solution during or
after polymerization. A skilled polymer chemist would know what
compounds would be suitable as acid scavengers and how much to use
with a particular reactive polymer and desired storage
stability.
Reactive Compositions
The reactive polymers described herein can be used in reactive
compositions incorporated into polymeric layers in various methods
for forming conductive patterns, for example using electroless
plating.
Each reactive composition has only one essential component, that
is, one or more reactive polymers as described above that can be
crosslinked in the crosslinkable groups upon exposure to radiation
having .lamda..sub.max of at least 150 nm and up to and including
700 nm, or of at least 150 nm and up to and including 450 nm, as
described below, and which reactive polymers also comprise pendant
water-solubilizing groups as described above. While various other
optional components can be included as described below, only the
reactive polymer is essential for providing the desired precursor
article, intermediate articles, product articles, and conductive
electroless metal plated pattern in the reactive composition
forming the polymeric layer as described herein.
One or more reactive polymers as described above are generally
present in the reactive composition (and in the resulting dry
polymeric layer) in an amount of at least 50 weight % and up to and
including 100 weight %, or typically at least 80 weight % and up to
and including 98 weight %, based on the total solids in the
reactive composition (or total dry weight of the polymeric
layer).
The reactive compositions generally do not include separate
crosslinking agents or crosslinking agent precursors because the
reactive polymer itself includes sufficient crosslinkable groups
(described above). However, as noted above, the --C-- recurring
units can also include additional crosslinking groups.
While not essential, it is sometimes desirable to enhance the
sensitivity of some reactive polymers to longer wavelengths (for
example, at least 300 nm and up to and including 700 nm, or at
least 150 nm and up to and including 450 nm) by including one or
more photosensitizers in the reactive composition used in this
invention. A variety of photosensitizers are known in the art such
as benzothiazole and naphthothiazole compounds as described in U.S.
Pat. No. 2,732,301 (Robertson et al.), aromatic ketones as
described in U.S. Pat. No. 4,507,497 (Reilly, Jr.), and
ketocoumarins, as described for example in U.S. Pat. No. 4,147,552
(Specht et al.) and U.S. Pat. No. 5,455,143 (Ali). Particularly
useful photosensitizers for long UV and visible light sensitivity
include but are not limited to,
2-[bis(2-furoyl)methylene]-1-methyl-naphtho[1,2-d]thiazoline,
2-benzoylmethylene-1-methyl-.beta.-napthothiazoline,
3,3'-carbonylbis(5,7-diethoxycoumarin),
3-(7-methoxy-3-coumarinoyl)-1-methylpyridinium fluorosulfate,
3-(7-methoxy-3-coumarinoyl)-1-methylpyridinium 4-toluenesulfonic
acid, and 3-(7-methoxy-3-coumarinoyl)-1-methylpyridinium
tetrafluoroborate. Other useful compounds are described in Columns
6 and 7 of U.S. Pat. No. 4,147,552 (noted above) which compounds
are incorporated herein by reference.
One or more photosensitizers can be present in the reactive
composition (and resulting dry polymeric layer) in an amount of at
least 0.1 weight % and up to and including 10 weight %, or more
likely at least 0.5 weight % and up to and including 5 weight %,
based on the total solids in the reactive composition (or total dry
weight of the polymeric layer).
The reactive compositions can optionally include one or more
addenda such as film-forming compounds, surfactants, plasticizers,
filter dyes, viscosity modifiers, and any other optional components
that would be readily apparent to one skilled in the art, and such
addenda can be present in amounts that would also be readily
apparent to one skilled in the art.
The essential reactive polymer and any optional compounds described
above are generally dissolved or dispersed in water or a mixture of
water and water-miscible organic solvents to form a reactive
composition that can be applied to a suitable substrate (described
below) in a suitable manner. Useful water-miscible organic solvents
include but are not limited to, alcohols such as methanol, ethanol,
and isopropanol and polyols such as ethylene glycol, propylene
glycol, and glycerol.
Articles
The reactive composition described above can be applied to a
suitable substrate using any suitable method including but not
limited to, spin coating, bead coating, blade coating, curtain
coating, or spray coating, from a suitable reservoir to form a
polymeric layer. Useful substrates can be chosen for particular use
or method as long as the substrate material will not be degraded by
the reactive composition or any treatments to which the resulting
precursor articles are subjected during the method of this
invention. The reactive composition can be applied multiple times
if desired to obtain a thicker coating (reactive polymer layer) of
the reactive composition, and dried between each coating or dried
only after the last application. Water and any water-miscible
organic solvents can be removed from the reactive composition using
any suitable drying technique.
In general, the final dry coating of reactive composition
(polymeric layer) can have an average dry thickness of at least 10
nm and up to and including 1 mm, with a dry thickness of at least
0.1 .mu.m and up to and including 100 .mu.m being more useful. The
average dry thickness can be determined by measuring the dry layer
thickness in at least 10 different places within a 10 cm by 10 cm
square of the dry reactive layer using an electron microscope or
other suitable analytical device.
Thus, useful substrates can be composed of glass, quartz, and
ceramics as well as a wide variety of flexible materials such as
cellulosic papers and polyesters including poly(ethylene
terephthalate) and poly(ethylene naphthalate), polycarbonates,
polyamides, poly(meth)acrylates, and polyolefins. Useful polymeric
substrates can be formed by casting or extrusion methods. Laminates
of various substrate materials can also be put together to form a
composite substrate. Any of the substrates can be treated to
improve adhesion using for example corona discharge, oxygen plasma,
ozone or chemical treatments using silane compounds such as
aminopropyltriethoxysilane. The substrates can be of any suitable
dry thickness including but not limited to at least 10 .mu.m and up
to and including 10 mm, depending upon the intended use of the
resulting articles.
Particularly useful substrates are composed of poly(ethylene
terephthalate) such as biaxially oriented poly(ethylene
terephthalate) (PET) films that have broad uses in the electronics
market. These PET films, ranging in dry thickness of at least 50
.mu.m and up to and including 200 .mu.m, can also comprise, on at
least one side, a polymeric primer layer (also known as a subbing
layer, adhesive layer, or binder layer) that can be added prior to
or after film stretching. Such polymeric primer layers can comprise
polyacrylonitrile-co-vinylidene chloride-co-acrylic acid),
poly(methyl acrylate-co-vinylidene chloride-co-itaconic acid),
poly(glycidyl methacrylate-co-butyl acrylate), or various
water-dispersible polyesters, water-dispersible polyurethanes, or
water-dispersible polyacrylics, as well as sub-micrometer silica
particles. The dry thickness of the primer layer can be at least
0.1 .mu.m and up to and including 1 .mu.m.
Thus, with the application of the described reactive composition to
a suitable substrate, with or without appropriate drying, the
present invention provides a precursor article comprising a
substrate and having disposed thereon a polymeric layer comprising
the reactive composition described above that comprises the
reactive polymer that is metal ion-complexing, water-soluble, and
crosslinkable, and optionally, a photosensitizer.
Uses of Reactive Compositions
The reactive compositions described herein can be used to form
reactive polymer patterns (or patterns of the reactive
compositions) that can be used as described below to form surface
conductive patterns for various purposes as described above. The
following discussion provides some details about representative
electroless plating methods in which the reactive compositions
described herein can be used.
In these electroless plating methods, each aqueous-based
"processing" solution, dispersion, or bath (for example, solutions
containing electroless seed metal ions, reducing agent solutions,
and solutions for electroless plating, as well as rinsing
solutions) used at various points can be specifically designed with
essential components as well as optional addenda that would be
readily apparent to one skilled in the art. For example, one or
more of those aqueous-based processing solutions can include such
addenda as surfactants, anti-coagulants, anti-corrosion agents,
anti-foamants, buffers, pH modifiers, biocides, fungicides, and
preservatives. The aqueous-based reducing solutions can also
include suitable antioxidants.
The method of this invention for forming a pattern in a polymeric
layer comprises:
providing a polymeric layer (as in forming the described precursor
article), the polymeric layer comprising the reactive composition
described above, comprising a reactive polymer as described above,
and optionally a photosensitizer. This polymeric layer can be
formed on a suitable substrate, if desired, as described above by
suitable application of the reactive composition, after which the
reactive composition is typically dried before the resulting
precursor article is used in the method of this invention.
This polymeric layer in the precursor article, usually in dry form,
can be then patternwise exposed to radiation having a
.lamda..sub.max of at least 150 nm and up to and including 700 nm
or to radiation having a .lamda..sub.max of at least 150 nm and up
to and including 450 nm, to provide a polymeric layer comprising
non-exposed regions and exposed regions comprising at least
partially crosslinked polymer. This exposure can be provided with
any suitable exposing source or device that provides the desired
radiation including but not limited to, various arc lamps and LED
sources. The particular exposing source can be chosen depending
upon the absorption characteristics of the reactive composition
used. The exposing radiation can be projected through lenses and
mirrors or through a lens or mask element that can be in physical
contact or in proximity with the outer surface of the polymeric
layer. Exposure time can range from a fraction (0.1) of a second
and up to and including 10 minutes depending upon the intensity of
the radiation source and the reactive composition. Suitable masks
can be obtained by known methods including but not limited to
photolithographic methods, flexographic methods, or vacuum
deposition of a chrome mask onto a suitable substrate such as
quartz or high quality optical glass followed by photolithographic
patterning.
It is optional but desirable to heat or bake the polymeric layer in
the precursor article simultaneously with or after the patternwise
exposure but generally before removing the reactive composition as
described below, at a temperature sufficient to further crosslink
the at least partially crosslinked in the exposed regions of the
polymeric layer. In most embodiments, this heating is carried out
at least after the patternwise exposure of the polymeric layer, but
it can be carried out both during and after the patternwise
exposure of the polymeric layer. Such heating can be accomplished
on a hot plate with vacuum suction to hold the precursor article in
close contact with the heating surface. Alternatively, the heating
device can be a convection oven. The duration of the heating
procedure is generally less than 10 minutes with heating for least
10 seconds and up to and including 5 minutes being most likely. The
optimal heating time and temperature can be readily determined with
routine experimentation depending upon the particular reactive
composition.
This results in an intermediate article of this invention
comprising a substrate and having disposed thereon a polymeric
layer comprising exposed regions and non-exposed regions,
the exposed regions comprising a pattern of at least partially
crosslinked polymer that has been derived from a reactive polymer
that is metal ion-complexing, water-soluble, and crosslinkable,
which reactive polymer comprises pendant groups comprising
crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- or
--C(.dbd.O)--CR.dbd.CR.sup.1--Y groups wherein R, R.sup.1, and Y
are as defined above, and
the non-exposed regions comprising a reactive composition that
comprises the reactive polymer, and optionally, a photosensitizer
as described above.
The polymeric layer is generally hydrophilic in the crosslinked and
exposed regions such that immersion in aqueous-based solutions
(described below) will allow the aqueous molecules, ions, or
reagent molecules to rapidly diffuse into the exposed regions.
After the imagewise exposure and optional heating procedures, the
reactive composition comprising the reactive polymer can be removed
from the non-exposed regions in the intermediate article so that
there is essentially no (less than 20%, and preferably less than
10%, by weight of the original amount) reactive composition
remaining on the substrate. This can be done by washing, spraying,
or immersing the intermediate article in water, aqueous alkaline
solution, or another aqueous solution for a suitable time and
temperature to remove most or all of the reactive composition from
the non-crosslinked, non-exposed regions of the polymeric layer.
Contact with the aqueous solution can be carried out for a suitable
time and temperature so that reactive composition is desirably
removed in the non-exposed regions but little removal occurs in the
exposed regions containing the crosslinked polymer. For example,
the contact time can be at least 10 seconds and up to and including
10 minutes, and the contact temperature can be at room temperature
(about 20.degree. C.) and up to and including 95.degree. C.
This procedure thus provides another intermediate article of this
invention, comprising a substrate and having disposed thereon a
polymeric layer comprising exposed regions and non-exposed
regions,
the exposed regions comprising a pattern of at least partially
crosslinked polymer that has been derived from a reactive polymer
in a reactive composition as defined above, and
the non-exposed regions comprising substantially no reactive
composition.
Once the reactive composition has been removed from the non-exposed
regions, the exposed regions of the polymeric layer can be
contacted with an aqueous-based solution or dispersion of
electroless seed metal ions to form a pattern of electroless seed
metal ions in the exposed regions of the polymeric layer. There are
various ways that this contacting can be carried out. Typically,
the entire intermediate article is immersed within a dilute
aqueous-based solution, bath, or dispersion of the electroless seed
metal ions for a sufficient time to coordinate the optimum number
of electroless seed metal ions within the crosslinked polymer that
has been derived from the reactive polymer described above. For
example, this contact with the electroless seed metal ions can be
carried out for at least 1 second and up to and including 30
minutes, at room temperature (about 20.degree. C.) or at a higher
temperature of up to and including 95.degree. C. The time and
temperature for this contact can be optimized for a given reactive
composition and electroless seed metal ions that are to be
used.
Representative electroless seed metal ions that can be used in
these procedures are selected from the group consisting of silver
ions, platinum ions, palladium ions, gold ions, tin ions, rhodium
ions, iridium ions, nickel ions, and copper ions. Most noble metal
ions can serve as electroless seed metal ions in the present
invention. These electroless seed metal ions can be provided in the
form of a suitable metal salt or metal-ligand complex (that can
have an overall positive, negative, or neutral charge). Useful
materials of this type include but are not limited to, metal salts
and metal-ligand complexes of nitrates, halides, acetates,
cyanides, thiocyanates, amines, nitriles, and sulfates. Thus, the
electroless seed metal ions can be provided from simple salts or in
the form of metal-ligand complexes. The amount of metal salts or
metal-ligand complexes present in the aqueous-based solution would
be readily apparent to one skilled in the art and can be optimized
for a particular reactive composition and exposure procedure. For
example, the metal salts or metal-ligand complexes can be present
in the aqueous-based solution in an amount sufficient to provide at
least 0.00001 molar and up to and including 2 molar of the desired
electroless metal ions. In one embodiment, a 0.4 molar silver
nitrate solution can be used at room temperature to provide
electroless seed silver ions.
The contact with the electroless seed metal ions produces an
intermediate article comprising a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
the exposed regions comprising a pattern of electroless seed metal
ions complexed within the at least partially crosslinked polymer
derived from a reactive polymer in a reactive composition described
above, and
the non-exposed regions comprising substantially no electroless
seed metal ions or reactive composition as described above.
After the requisite time to react the electroless seed metal ions
within the at least partially crosslinked polymer in the exposed
regions, the polymeric layer can be rinsed with distilled or
deionized water or another aqueous-based solution for a suitable
time and at a suitable temperature, for example usually room
temperature or slightly higher.
After forming the pattern of electroless seed metal ions, the
electroless seed metal ions can be reduced to provide a pattern of
the corresponding electroless seed metal nuclei in the exposed
regions of the polymeric layer. This can be done by contacting the
polymeric layer (or at least the exposed regions) with a suitable
reducing agent for the electroless seed metal ions. For example,
the intermediate article comprising the polymeric layer can be
immersed within an aqueous-based reducing solution containing one
or more reducing agents for a suitable time to cause sufficient
metal ion reduction. Alternatively, an aqueous-based reducing
solution comprising the reducing agent can be sprayed or rolled
uniformly onto the polymeric layer.
Useful reducing agents include but are not limited to, an organic
borane, an aldehyde such as formaldehyde, aldehyde sugar,
hydroquinone, or sugar (or polysaccharide) such as ascorbic acid,
and metal ions such as tin(II). These reducing agents can be used
individually or in combination, and the total amount in the
aqueous-based reducing solution used for the reducing procedure can
be at least 0.01 weight % and up to and including 20 weight % based
on the total reducing solution weight. The amount of reducing agent
to be used will depend upon the particular electroless seed metal
ions and reducing agent to be used, and this can be readily
optimized using routine experimentation. The time and temperature
for the reduction can also be readily optimized in the same manner.
Generally, the reducing temperature is at least room temperature
(about 20.degree. C.) and up to and including 95.degree. C. and the
reducing time can be for at least 1 second and up to and including
30 minutes.
For example, some embodiments of the present invention can be
carried out using an immersion bath comprising 1 reducing solution
weight % of an organic borane such as dimethylamine borane (DMAB)
at room temperature for up to 3 minutes. Longer or shorter times at
higher temperatures are possible if needed.
After this reducing procedure, the polymeric layer, especially the
exposed regions, can be again washed using distilled water or
deionized water or another aqueous-based solution at a suitable
temperature for a suitable time.
At this point, the method of this invention has provided yet
another intermediate article, comprising a substrate and having
disposed thereon a polymeric layer comprising exposed regions and
non-exposed regions,
the exposed regions comprising a pattern of corresponding
electroless seed metal nuclei within the at least partially
crosslinked polymer that has been derived from the reactive polymer
in the reactive composition described above, and
the non-exposed regions comprising substantially no electroless
seed metal nuclei or reactive composition as described above.
This intermediate article can be immediately immersed in an
aqueous-based electroless metal plating bath or solution, or the
intermediate article can be stored with just the catalytic pattern
comprising corresponding electroless seed metal nuclei for use at a
later time.
The intermediate article can be contacted with an electroless
plating metal that is the same as or different from the
corresponding electroless seed metal nuclei. In most embodiments,
the electroless plating metal is a different metal from the
corresponding electroless seed metal nuclei.
Any metal that will likely electrolessly "plate" on the
corresponding electroless seed metal nuclei can be used at this
point, but in most embodiments, the electroless plating metal can
be for example copper(II), silver(I), gold(IV), palladium(II),
platinum(II), nickel(II), chromium(II), and combinations thereof.
Copper(II), silver(I), and nickel(II) are particularly useful
electroless plating metals.
The one or more electroless plating metals can be present in the
aqueous-based electroless plating bath or solution in an amount of
at least 0.01 weight % and up to and including 20 weight % based on
total solution weight.
Electroless plating can be carried out using known temperature and
time conditions, as such conditions are well known in various
textbooks and scientific literature. It is also known to include
various additives such as metal complexing agents or stabilizing
agents in the aqueous-based electroless plating solutions.
Variations in time and temperature can be used to change the metal
electroless plating thickness or the metal electroless plating
deposition rate.
A useful aqueous-based electroless plating solution or bath is an
electroless copper(II) plating bath that contains formaldehyde as a
reducing agent. Ethylenediaminetetraacetic acid (EDTA) or salts
thereof can be present as a copper complexing agent. For example,
copper electroless plating can be carried out at room temperature
for several seconds and up to several hours depending upon the
desired deposition rate and plating rate and plating metal
thickness.
Other useful aqueous-based electroless plating solutions or baths
comprise silver(I) with EDTA and sodium tartrate, silver(I) with
ammonia and glucose, copper(II) with EDTA and dimethylamineborane,
copper(II) with citrate and hypophosphite, nickel(II) with lactic
acid, acetic acid, and a hypophosphite, and other industry standard
aqueous-based electroless baths or solutions such as those
described by Mallory et al. in Electroless Plating: Fundamentals
and Applications 1990.
After the electroless plating procedure, the resulting product
article is removed from the aqueous-based electroless plating bath
or solution and can again be washed using distilled water or
deionized water or another aqueous-based solution to remove any
residual electroless plating chemistry. At this point, the
polymeric layer and electrolessly plated metal are generally stable
and can be used for their intended purpose.
Thus, this method provides a product article comprising a substrate
and having disposed thereon a polymeric layer comprising exposed
regions and non-exposed regions,
the exposed regions comprising a pattern of corresponding
electroless seed metal nuclei that have been electrolessly plated
with the same or different metal within the at least partially
crosslinked polymer derived from the reactive polymer in a reactive
composition as described above, and
the non-exposed regions comprising substantially no electrolessly
plated metal or reactive composition as described above.
To change the surface of the electroless plated metal for visual or
durability reasons, it is possible that a variety of
post-treatments can be employed including surface plating of still
at least another (third or more) metal such as nickel or silver on
the electrolessly plated metal (this procedure is sometimes known
as "capping"), or the creation of a metal oxide, metal sulfide, or
a metal selenide layer that is adequate to change the surface color
and scattering properties without reducing the conductivity of the
electrolessly plated (second) metal. Depending upon the metals used
in the various capping procedures of the method, it may be
desirable to treat the electrolessly plated metal with a seed metal
catalyst in an aqueous-based seed metal catalyst solution to
facilitate deposition of additional metals.
As one skilled in the art should appreciate, the individual
treatments or steps described above for this method can be carried
out two or more times before proceeding to the next procedure or
step. For example, the treatment with the aqueous-based solution
containing electroless seed metal ions can be carried out two or
more times in sequence, for example, with a rinsing step between
sequential treatments. The electroless seed metal ions can be the
same or different for the sequential treatments and the treatment
conditions can be the same or different.
In addition, multiple treatments with an aqueous-based reducing
solution or aqueous-based electroless metal plating solution can be
carried out in sequence, using the same or different conditions.
Sequential washing or rinsing steps can also be carried out where
appropriate.
Further, the electroless plating procedures can be carried out
multiple times, in sequence, using the same or different
electroless plating metal and the same or different electroless
plating conditions.
The reactive polymers and reactive compositions described above can
also be used in additional patterning methods described as
follows:
Electroless Plating Method 2:
This method can be used to form a pattern in a polymeric layer, the
method comprising:
providing a polymeric layer comprising a reactive composition that
comprises: (1) a reactive polymer, and (2) optionally, a
photosensitizer, as described above,
patternwise exposing the polymeric layer to radiation having a
.lamda..sub.max of at least 150 nm that is sufficient to induce
crosslinking within the reactive polymer, to provide a polymeric
layer comprising non-exposed regions and exposed regions comprising
an at least partially crosslinked polymer derived from the reactive
polymer,
optionally heating the polymeric layer simultaneously with or after
patternwise exposing the polymeric layer but before removing the
reactive composition comprising the reactive polymer in the
non-exposed regions, at a temperature sufficient to further
crosslink the at least partially crosslinked polymer in the exposed
regions of the polymeric layer,
removing the reactive composition comprising the reactive polymer
in the non-exposed regions,
incorporating a reducing agent into the exposed regions of the
polymeric layer,
contacting the exposed regions of the polymeric layer with
electroless seed metal ions to oxidize the reducing agent in the
exposed regions of the polymeric layer and to form a pattern of
electroless seed metal nuclei in the exposed regions of the
polymeric layer, and
electrolessly plating the corresponding electroless seed metal
nuclei in the exposed regions of the polymeric layer with a metal
that is the same as or different from the corresponding electroless
seed metal nuclei.
The polymeric layer in a precursor article, usually in dry form,
can be then patternwise exposed to radiation having a
.lamda..sub.max of at least 150 nm and up to and including 450 nm
or to radiation having a .lamda..sub.max of at least 150 nm and up
to and including 330 nm, as described above.
It is optional but desirable to heat or bake the reactive
composition in the precursor article simultaneously with or after
the patternwise exposure but generally before contacting the
exposed polymeric layer with the aqueous-based reducing solution
(described below) and conditions as described above.
Generally immediately after the patternwise exposing or optional
heating procedures, the reactive composition in the non-exposed
regions of the polymeric layer is removed as described above in
prior methods. Upon this removal of reactive composition from the
non-exposed regions of the polymeric layer, the various articles
described herein will contain crosslinked polymer in the exposed
regions of the polymeric layer.
At this point, an intermediate article has been created in which
the exposed regions of the polymeric layer on the substrate
comprise crosslinked polymer derived from the reactive polymer in
the reactive composition as described herein, and the non-exposed
regions of the polymeric layer comprise little or no reactive
composition (less than 10 weight % of the original amount).
After the exposure and optional heating, the exposed regions of the
polymeric layer are contacted with an aqueous-based reducing
solution containing one or more reducing agents and conditions, as
described above. In the exposed regions, the reducing agent can
diffuse into the crosslinked polymer provided during irradiation or
the reactive composition described herein. In the non-exposed
regions, the reducing agent does not readily diffuse into or attach
to the reactive polymer.
After this reducing procedure, the polymeric layer, especially the
exposed regions, can be again washed using distilled water or
deionized water or another aqueous-based solution at a suitable
temperature for a suitable time.
At this point, an intermediate article is provided, which
intermediate article comprises a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
the exposed regions comprising a pattern of a crosslinked polymer
derived from the reactive polymer in the reactive composition
described herein, and comprising reducing agent dispersed within
the crosslinked polymer, and
the non-exposed regions comprising substantially no reactive
composition.
Once the patternwise exposure, optional heating, and contacting
with the reducing agent have been carried out, the exposed regions
of the polymeric layer can be contacted with an aqueous-based
solution or dispersion of electroless seed metal ions to form
electroless seed metal nuclei in the exposed regions of the
polymeric layer using aqueous-based solutions and conditions as
described above. These electroless seed metal nuclei form catalytic
sites for electroless metal plating (deposition of metal) described
below.
The contact with the electroless seed metal ions produces an
intermediate article comprising a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
the exposed regions comprising a pattern of electroless seed metal
nuclei within the crosslinked polymer resulting from the
irradiation of the reactive polymer in the reactive composition
described herein, and
the non-exposed regions comprising substantially no reactive
composition.
After the requisite time to react within the resulting crosslinked
polymer in the exposed regions, the polymeric layer can be rinsed
with distilled or deionized water or other aqueous-based solution
for a suitable time and at a suitable temperature, usually room
temperature or slightly higher.
The resulting intermediate article can be immediately immersed in
an aqueous-based electroless plating bath or solution or the
immediate article can be stored with the catalytic pattern
comprising corresponding electroless seed metal nuclei for use at a
later time. The intermediate article can be contacted with an
electroless plating metal that is the same as or different from the
corresponding electroless seed metal nuclei, using aqueous-based
solutions and conditions as described above.
After the electroless plating procedure, a product article is
removed from the aqueous-based electroless plating bath and can
again be washed using distilled water or deionized water or another
aqueous-based solution to remove any residual electroless plating
chemistry. At this point, the polymeric layer and electrolessly
plated metal are generally stable and can be used for their
intended purpose.
Thus, this method provides a product article comprising a substrate
and having disposed thereon a polymeric layer comprising exposed
regions and non-exposed regions,
the exposed regions comprising a pattern of an electroless seed
metal nuclei (for example, in a pattern) that have been
electrolessly plated with the same or different metal, and
crosslinked polymer resulting from irradiation of the reactive
polymer in the reactive composition described above, and
the non-exposed regions comprising substantially no reactive
composition.
Electroless Plating Method 3:
This method can be used to form a pattern in a polymeric layer, the
method comprising:
providing a polymeric layer comprising a reactive composition that
comprises: (1) a reactive polymer, and (2) optionally, a
photosensitizer, as described above,
patternwise exposing the polymeric layer to radiation having a
.lamda..sub.max of at least 150 nm that is sufficient to induce
crosslinking within the reactive polymer, to provide a polymeric
layer comprising non-exposed regions and exposed regions comprising
an at least partially crosslinked polymer derived from the reactive
polymer,
optionally heating the polymeric layer simultaneously with or after
patternwise exposing the polymeric layer but before removing the
reactive composition comprising the reactive polymer in the
non-exposed regions, at a temperature sufficient to further
crosslink the at least partially crosslinked polymer in the exposed
regions of the polymeric layer,
removing the reactive composition comprising the reactive polymer
in the non-exposed regions,
contacting both the non-exposed regions and the exposed regions of
the polymeric layer with a reducing agent,
bleaching the polymeric layer to remove surface amounts of the
reducing agent in both non-exposed and exposed regions of the
polymeric layer,
contacting the exposed regions of the polymeric layer with
electroless seed metal ions to oxidize the reducing agent and to
form a pattern of electroless seed metal nuclei in the exposed
regions of the polymeric layer, and
electrolessly plating the corresponding electroless seed metal
nuclei in the exposed regions of the polymeric layer with a metal
that is the same as or different from the corresponding electroless
seed metal nuclei.
Thus, in this method including providing a polymeric layer (as in
forming the described precursor article), the polymeric layer
comprises a reactive composition comprising a reactive polymer and
optionally, a photosensitizer, all as described above.
This polymeric layer in the precursor article, usually in dry form,
can be then patternwise exposed to radiation having a
.lamda..sub.max of at least 150 nm and up to and including 450 nm
or to radiation having a .lamda..sub.max of at least 150 nm and up
to and including 330 nm, as described above.
It is optional but desirable to heat or bake the reactive
composition in the precursor article simultaneously with or after
the patternwise exposure but generally before contacting the
exposed polymeric layer with electroless seed metal ions (described
below), as described above.
Generally immediately after the patternwise exposing or optional
heating procedures, the reactive composition remaining in the
non-exposed regions of the polymeric layer is removed as described
above in previous methods (at least 90 weigh % of the original
amount).
At this point, an intermediate article has been created in which
the exposed regions of the polymeric layer on the substrate
comprise crosslinked polymer derived from the reactive polymer in
the reactive composition described above, and the non-exposed
regions of the polymeric layer comprise little or no reactive
composition.
After the exposure and optional heating, the exposed regions of the
polymeric layer are contacted with an aqueous-based reducing
solution containing one or more suitable reducing agents using
aqueous-based solutions and conditions as described above. In the
exposed regions, the reducing agent can diffuse into the
crosslinked polymer. In the non-exposed regions, the reducing agent
does not readily diffuse into the polymeric layer but will become
attached to the surface of the polymeric layer.
After this reducing procedure, the polymeric layer, especially the
exposed regions, can be again washed using distilled water or
deionized water or another aqueous-based solution at a suitable
temperature for a suitable time.
At this point, an intermediate article is provided, which
intermediate article comprises a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
the exposed regions comprising a crosslinked polymer derived from
the reactive polymer in the reactive composition described above,
into which a reducing agent has diffused, and
the non-exposed regions comprising substantially no reducing agent
and reactive composition (less than 10 weight % of the original
amount).
Once patternwise exposure, optional heating, and the reducing
procedure have been carried out, the polymeric layer can be
contacted with an aqueous-based bleaching (or oxidizing) solution
comprising one or more bleaching agents, thereby removing surface
amounts of the reducing agent in both non-exposed and exposed
regions of the polymeric layer. The term "bleaching" refers to
oxidizing the reducing agent molecules to make them inactive for
further reaction (thus, they cannot reduce the seedless metal ions
when bleached).
Useful bleaching agents for this bleaching procedure can be chosen
depending upon the reducing agent that is used in the previous
operation. Representative bleaching agents include but are not
limited to, peroxides such as hydrogen peroxide, persulfates,
iron(III) complexes, and combinations thereof. Hydrogen peroxide is
particularly useful. In general, the one or more bleaching agents
are present in the aqueous-based bleaching solution in an amount of
at least 0.01 weight % and up to and including 20 weight %, based
on total aqueous-based bleaching solution weight.
In general, bleaching the polymeric layer is carried out in
sufficient time and temperature so that the aqueous-based bleaching
solution reacts with (deactivates) or removes at least 90 mol % (or
typically at least 95 mol %) of the reducing agent in the
non-exposed regions and less than 40 mol % (or typically less than
25 mol %) in the exposed regions of the polymeric layer. The useful
time and temperature conditions needed to achieve these results
would be readily determined with routine experimentation in view of
the teaching provided herein.
At this point, the present invention provides an intermediate
article, comprising a substrate and having disposed thereon a
polymeric layer comprising exposed regions and non-exposed
regions,
the exposed regions comprising a pattern of non-oxidized reducing
agent molecules within the crosslinked polymer resulting from the
irradiation of the reactive polymer in the reactive composition
described herein, and
the non-exposed regions comprising substantially no reactive
composition.
Once the previous operations have been carried out, the exposed
regions of the polymeric layer can be contacted with an
aqueous-based solution or dispersion containing electroless seed
metal ions to oxidize the reducing agent and to form corresponding
electroless seed metal nuclei (for example in a pattern) in the
exposed regions of the polymeric layer using aqueous-based
solutions and conditions as described above. These corresponding
electroless seed metal nuclei form catalytic sites for electroless
metal plating (deposition of metal) described below.
The contact with the electroless seed metal ions produces an
intermediate article comprising a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
the exposed regions comprising a pattern of corresponding
electroless seed metal nuclei within the crosslinked polymer
resulting from irradiation of the reactive polymer in the reactive
composition described herein, and
the non-exposed regions comprising substantially no reactive
composition.
After the requisite time to react the electroless seed metal ions
within the resulting crosslinked polymer in the exposed regions,
the polymeric layer can be rinsed with distilled or deionized water
or another aqueous-based solution for a suitable time and at a
suitable temperature, usually room temperature or slightly
higher.
The resulting intermediate article can be immediately immersed in
an aqueous-based electroless plating bath or solution or it can be
stored with just the catalytic pattern comprising electroless seed
metal for use at a later time.
The article can be contacted with an electroless plating metal that
is the same as or different from the electroless seed metal using
aqueous-based solutions and conditions as described above. In most
embodiments, the electroless plating metal is a metal different
from the corresponding electroless seed metal nuclei.
After the electroless plating procedure, the product article is
removed from the aqueous-based electroless plating bath and can
again be washed using distilled water or deionized water or another
aqueous-based solution to remove any residual electroless plating
chemistry. At this point, the polymeric layer and electrolessly
plated metal are generally stable and can be used for their
intended purpose.
Thus, this method provides a product article comprising a substrate
and having disposed thereon a polymeric layer comprising exposed
regions and non-exposed regions,
the exposed regions comprising a pattern of a corresponding
electroless seed metal nuclei within the crosslinked polymer
derived from the reactive polymer in the reactive composition
described herein, which has been electrolessly plated with the same
or different metal, and
the non-exposed regions comprising substantially no reactive
composition or electroless seed metal nuclei.
Electroless Plating Method 4:
This method can be used to form a pattern in a polymeric layer, the
method comprising:
providing a polymeric layer comprising a reactive composition that
comprises: (1) a reactive polymer, and (2) optionally, a
photosensitizer, as described above,
patternwise exposing the polymeric layer to radiation having a
.lamda..sub.max of at least 150 nm that is sufficient to induce
crosslinking within the reactive polymer, to provide a polymeric
layer comprising non-exposed regions and first exposed regions
comprising an at least partially crosslinked polymer derived from
the reactive polymer,
optionally heating the polymeric layer simultaneously with or after
patternwise exposing the polymeric layer but before removing the
reactive composition comprising the reactive polymer in the
non-exposed regions, at a temperature sufficient to further
crosslink the at least partially crosslinked polymer in the first
exposed regions of the polymeric layer,
removing the reactive composition comprising the reactive polymer
in the non-exposed regions (at least 90 weight % of the original
amount),
contacting the first exposed regions of the polymeric layer with
electroless seed metal ions to form electroless seed metal ions in
the first exposed regions of the polymeric layer,
contacting the first exposed regions of the polymeric layer with a
halide to react with the electroless seed metal ions and to form
corresponding electroless seed metal halide in the first exposed
regions of the polymeric layer,
optionally exposing the polymeric layer to convert at least some of
the corresponding electroless seed metal halide in the first
exposed regions to corresponding electroless seed metal nuclei and
to form second exposed regions in the polymeric layer,
optionally contacting the polymeric layer with a reducing agent
either: (i) to develop the corresponding electroless seed metal
image in the second exposed regions of the polymeric layer, or (ii)
to develop all of the corresponding electroless seed metal halide
in the first exposed regions,
optionally contacting the polymeric layer with a fixing agent to
remove any remaining corresponding electroless seed metal halide in
either the first exposed regions, the second exposed regions, or
both of the first exposed regions and the second exposed regions,
and
electrolessly plating the corresponding electroless seed metal
nuclei in the first exposed regions, the second exposed regions, or
both the first exposed regions and the second exposed regions, of
the polymeric layer with a metal that is the same as or different
from the corresponding electroless seed metal nuclei.
Such method is carried out by providing a polymeric layer (as in
forming the described precursor article), the polymeric layer
comprising the reactive composition described above. This polymeric
layer in the precursor article, usually in dry form, can be then
patternwise exposed to radiation having a .lamda..sub.max of at
least 150 nm and up to and including 450 nm or to radiation having
a .lamda..sub.max of at least 150 nm and up to and including 330
nm, as described above to provide a polymeric layer comprising
non-exposed regions and first exposed regions comprising a
crosslinked polymer.
It is optional but desirable to heat or bake the reactive
composition in the precursor article simultaneously with or after
the patternwise exposure but generally before contacting the
exposed polymeric layer with electroless seed metal ions (described
below), as described above.
Generally immediately after the patternwise exposing or optional
heating procedures, the reactive composition remaining in the
non-exposed regions of the polymeric layer is removed as described
above for other methods (at least 90 weight % of the original
amount). Upon this removal of reactive composition from the
non-exposed regions of the polymeric layer, the various articles
described herein will contain crosslinked polymer in the exposed
regions of the polymeric layer.
At this point, an intermediate article has been created in which
the first exposed regions of the polymeric layer on the substrate
comprise crosslinked polymer derived from the reactive polymer in
the reactive composition described above, and the non-exposed
regions of the polymeric layer comprise substantially no reactive
composition.
Once patternwise exposure and optional heating have been carried
out, the first exposed regions of the polymeric layer are contacted
with electroless seed metal ions to form coordinated electroless
seed metal ions in the first exposed regions of the polymeric layer
using aqueous-based solutions and conditions described above.
The contact with the electroless seed metal ions produces an
intermediate article comprising a substrate and having disposed
thereon a polymeric layer comprising first exposed regions and
non-exposed regions,
the first exposed regions comprising a pattern of electroless seed
metal ions within the crosslinked polymer resulting from
irradiation of the reactive polymer in the reactive composition
described above, and
the non-exposed regions comprising substantially no reactive
composition.
After the requisite time to react the electroless seed metal ions
within the crosslinked polymer in the first exposed regions, the
polymeric layer can be rinsed with distilled or deionized water or
another aqueous-based solution for a suitable time and at a
suitable temperature, usually room temperature or slightly
higher.
At least the first exposed regions of the polymeric layer are then
contacted with a halide that reacts with the seed metal ions to
form corresponding electroless seed metal halide in the first
exposed regions of the polymeric layer. Halides can be provided as
suitable halide salts to provide iodide ions, chloride ions, or
bromide ions or a combination of two or more of these halides to
form electroless seed metal halide in the first exposed regions of
the polymeric layer. Chloride ions, iodide ions, or bromide ions or
mixtures thereof are particularly useful.
This contacting with a halide can be carried out by immersing the
intermediate article described above within an aqueous-based halide
bath or halide solution of a suitable halide salt, or the
aqueous-based halide solution can be sprayed or coated onto the
polymeric layer in a uniform or patternwise manner. The time for
this halide treatment can be at least 1 second and up to and
including 30 minutes, and the temperature for the halide treatment
can be room temperature (about 20.degree. C.) and up to and
including 95.degree. C. The time and temperature and the type and
amount of halide in a treatment bath can be optimized in order to
provide the sufficient amount of corresponding electroless seed
metal halide in the first exposed regions of the polymeric
layer.
At this point, an intermediate article has been created, which
intermediate article comprises a substrate and having thereon a
polymeric layer comprising first exposed regions and non-exposed
regions,
the first exposed regions of the polymeric layer comprising a
pattern of corresponding electroless seed metal halide in the
crosslinked polymer derived from the reactive polymer in the
reactive composition described above, and
the non-exposed regions comprising substantially no reactive
composition.
After this halide treatment, the polymeric layer can be optionally
exposed again to convert at least some, or typically at least 20%
(or more typically at least 50%), of the corresponding electroless
seed metal halide in first exposed regions of the polymeric layer
to corresponding electroless seed metal nuclei using radiation
having a .lamda..sub.max of at least 150 nm and up to and including
450 nm, or more likely having a .lamda..sub.max of at least 240 nm
and up to and including 450 nm. The second exposed regions can be
the same as or different from the first exposed regions, or the
first and second exposed regions can partially overlap.
With this second exposure, the method can provide yet another
intermediate article comprising a substrate and having disposed
thereon a polymeric layer comprising first exposed regions, second
exposed regions, and non-exposed regions,
the first exposed regions comprising corresponding electroless seed
metal halide in the crosslinked polymer derived from the reactive
polymer in the reactive composition described above,
the second exposed regions comprising a pattern of corresponding
electroless seed metal with a latent image in the crosslinked
polymer derived from the reactive polymer in the reactive
composition described above, and
the non-exposed regions comprising substantially no reactive
composition as described above.
The polymeric layer comprising corresponding electroless seed metal
halide in the first exposed regions, or corresponding electroless
seed metal latent image in the second exposed regions, or both
corresponding electroless seed metal halide in the first exposed
regions and corresponding electroless seed metal latent image in
the second exposed regions are then optionally contacted with a
suitable aqueous-based reducing solution comprising one or more
reducing agents using aqueous-based solutions and conditions as
described above.
After this reducing procedure, the polymeric layer, especially the
first exposed regions or the second exposed regions, can be again
washed using distilled water or deionized water or another
aqueous-based solution for a suitable time to remove excess
reducing agent.
The reducing procedure can provide another intermediate article
that comprises a substrate and having thereon a polymeric layer
comprising first exposed regions, second exposed regions, and
non-exposed regions,
the first exposed regions of the polymeric layer comprising a
pattern of corresponding electroless seed metal halide in a
crosslinked polymer derived from the reactive polymer in the
reactive composition described above,
the second exposed regions of the polymeric layer comprising a
pattern of corresponding electroless seed metal nuclei in the
crosslinked polymer derived from the reactive polymer in the
reactive composition described above, and
the non-exposed regions of the polymeric layer comprising
substantially no reactive composition.
The polymeric layer comprising corresponding electroless seed metal
halide in the first exposed regions, or corresponding electroless
seed metal nuclei in the second exposed regions, or both
corresponding electroless seed metal halide in the first exposed
regions and corresponding electroless seed metal nuclei in the
second exposed regions, are then optionally contacted with a
suitable fixing agent. This contact removes any remaining
corresponding electroless seed metal halide from both the first
exposed regions and the second exposed regions of the polymeric
layer, while leaving behind any corresponding electroless seed
metal nuclei in the second exposed regions.
This contact with a fixing agent can be done by immersing the
polymeric layer (or at least the first and second exposed regions)
within an aqueous-based fixing solution containing one or more
fixing agents for a suitable time to cause the desired change
(removal of the corresponding electroless metal halide) in the
first exposed regions and the second exposed regions.
Alternatively, an aqueous-based fixing solution can be sprayed or
rolled uniformly onto the polymeric layer to accomplish the same
results.
Useful fixing agents include but are not limited to, sulfites,
thiocyanates, thiosulfates, thioureas, halides, ammonia, chelates
such as ethylenediaminetetracetic acid, and mixtures thereof.
Fixing accelerators can also be included in the aqueous-based
fixing solutions, which compounds include, but are not limited to,
thioethers and mercaptotriazoles. The fixing agents can be present
as salts (that is alkali metal or ammonium salts) as is well known
in the art, for instance as described in Research Disclosure
December 1978 publication 38957. The total amount of fixing agents
in the aqueous-based fixing solution can be at least 0.01 weight %
and up to and including 50 weight % based on total fixing solution
weight. The fixing agent amount can be readily optimized using
routine experimentation. The fixing time and temperature can also
be readily optimized in the same manner. Generally, the fixing
temperature is at least room temperature (about 20.degree. C.) and
up to and including 99.degree. C. and the reducing time can be for
at least 1 second and up to and including 30 minutes.
For example, some embodiments of the present invention can be
carried out using an aqueous-based fixing solution comprising 20
solution weight % of sodium thiosulfate in combination with 1.5
solution weight % of sodium sulfite at room temperature for 3
minutes. Longer or shorter times at higher temperatures are
possible.
After this fixing procedure, the polymeric layer, especially the
first exposed regions or the second exposed regions, can be again
washed using distilled water or deionized water or another
aqueous-based solution for a suitable time to remove excess fixing
agent.
The fixing procedure can provide another intermediate article that
comprises a substrate and having thereon a polymeric layer
comprising first exposed regions, second exposed regions, and
non-exposed regions,
the first exposed regions of the polymeric layer from which the
pattern of corresponding electroless seed metal halide has been
removed, the first exposed regions comprising the crosslinked
polymer being derived from a reactive polymer in a reactive
composition as described above,
the second exposed regions of the polymeric layer comprising a
pattern of corresponding electroless seed metal nuclei in the
crosslinked polymer being derived from a reactive polymer in a
reactive composition as described above, and
the non-exposed regions of the polymeric layer comprising
substantially no reactive composition.
The intermediate article that has been treated as described above
can be immediately immersed in an aqueous-based electroless metal
plating bath or solution using conditions and aqueous-based
solutions described above, or the treated article can be stored
with just the catalytic pattern comprising corresponding
electroless seed metal nuclei for use at a later time.
After the electroless plating procedure, the product article is
removed from the aqueous-based electroless plating bath or solution
and can again be washed using distilled water or deionized water or
another aqueous-based solution to remove any residual electroless
plating chemistry. At this point, the polymeric layer and
electrolessly plated metal are generally stable and can be used for
their intended purpose.
Thus, this method provides a product article comprising a substrate
and having disposed thereon a polymeric layer comprising first
exposed regions (and optional second exposed regions) and
non-exposed regions,
the first exposed regions comprising a pattern of corresponding
electroless seed metal nuclei that have been electrolessly plated
with the same or different metal in a crosslinked polymer derived
from the a reactive polymer in the reactive composition described
herein, and
the non-exposed regions comprising substantially no reactive
composition.
Electroless Plating Method 5:
This method can be used to form a pattern in a polymeric layer, the
method comprising:
providing a polymeric layer comprising a reactive composition that
comprises: (1) a reactive polymer, and (2) optionally, a
photosensitizer, as described above,
patternwise exposing the polymeric layer to radiation having a
.lamda..sub.max of at least 150 nm that is sufficient to induce
crosslinking within the reactive polymer, to provide a polymeric
layer comprising non-exposed regions and exposed regions comprising
an at least partially crosslinked polymer derived from the reactive
polymer,
optionally heating the polymeric layer simultaneously with or after
patternwise exposing the polymeric layer but before removing the
reactive composition comprising the reactive polymer in the
non-exposed regions, at a temperature sufficient to further
crosslink the at least partially crosslinked polymer in the exposed
regions of the polymeric layer,
removing the reactive composition comprising the reactive polymer
in the non-exposed regions (at least 90 weight % of the original
amount),
contacting the exposed regions of the polymeric layer with
electroless seed metal ions to form a pattern of electroless seed
metal ions in the exposed regions of the polymeric layer,
optionally contacting the pattern of electroless seed metal ions in
the exposed regions of the polymeric layer with a non-reducing
reagent that reacts with the electroless seed metal ions to form an
electroless seed metal compound that has a K.sub.sp of less than
40, and
electrolessly plating the electroless seed metal compound within
the exposed regions of the polymeric layer with a metal that is the
same as or different from the corresponding electroless seed metal
compound.
Such method thus comprises providing a polymeric layer (as in
forming the described precursor article), the polymeric layer
comprising a reactive composition as described above comprising a
reactive polymer and optionally, a photosensitizer.
This polymeric layer in the precursor article, usually in dry form,
can be then patternwise exposed as described above to radiation
having a .lamda..sub.max of at least 150 nm and up to and including
450 nm or to radiation having a .lamda..sub.max of at least 150 nm
and up to and including 330 nm, to provide a polymeric layer
comprising non-exposed regions and exposed regions comprising a
crosslinked polymer.
It is optional but desirable to heat or bake the polymeric layer in
the precursor article simultaneously with or after the patternwise
exposure but generally before contacting the exposed polymeric
layer with electroless seed metal ions (described below) using
conditions described above.
Generally, immediately after the patternwise exposing or optional
heating procedures, the reactive composition remaining in the
non-exposed regions of the polymeric layer is removed as described
above for previous methods.
At this point, an intermediate article has been created in which
the exposed regions of the polymeric layer on the substrate
comprise crosslinked polymer derived from the reactive polymer in
the reactive composition described above, and the non-exposed
regions of the polymeric layer comprise substantially reactive
composition.
Then, the exposed regions of the polymeric layer are contacted with
electroless seed metal ions to form coordinated electroless seed
metal ions in the exposed regions of the polymeric layer using
aqueous-based solutions and conditions as described above.
The contact with the electroless seed metal ions produces an
intermediate article comprising a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
the exposed regions comprising a pattern of electroless seed metal
ions within the crosslinked polymer resulting from the irradiation
of the reactive polymer in the reactive composition described
herein, and
the non-exposed regions comprise substantially no reactive
composition.
After the requisite time to react the electroless seed metal ions
within the crosslinked polymer in the exposed regions, the
polymeric layer can be rinsed with distilled or deionized water or
another aqueous-based solution for a suitable time and at a
suitable temperature, for example usually room temperature or
slightly higher.
The electroless seed metal ions in the exposed regions of the
polymeric layer are then contacted with a non-reducing reagent that
reacts with the electroless seed metal ions to form an electroless
seed metal compound (containing the non-reducing reagent) deposited
within the exposed regions of the polymeric layer containing the
crosslinked polymer derived from the reactive polymer in the
reactive composition described above.
Useful non-reducing reagents include any compound that will
covalently, ionically, or otherwise bond to or react with the
electroless seed metal ions to form the electroless seed metal
compound. Useful non-reducing reagents include those that provide
electroless seed metal compounds having a pK.sub.sp value of less
than 40, and for example, a pK.sub.sp that is greater than 4 and
less than 40. For example, such useful non-reducing reagents
include but are not limited to, alkali metal and ammonium
hydroxides, thiosulfates, thiocyanates, sulfites, small organic
acids, and combinations thereof. Halides are also useful
non-reducing reagents for this invention. Alkali metal hydroxides
are particularly useful including mixtures thereof.
This contacting procedure can be carried out in various ways
including immersing the intermediate article in an aqueous-based
non-reducing solution comprising one or more non-reducing reagents
at a concentration of at least 1 weight % based on total
aqueous-based non-reducing solution weight. Alternatively, an
aqueous-based non-reducing solution can be sprayed or coated onto
the polymeric layer in the intermediate article. The time and
temperature for this contacting would be readily apparent to one
skilled in the art in order to best achieve the desired bonding.
For example, the contacting can be carried out at room temperature
(about 20.degree. C.) and up to and including 95.degree. C. and the
time can be for at least 1 second and up to and including 30
minutes.
After this contact with the non-reducing reagent, the polymeric
layer, especially the exposed regions, can be again washed using
distilled water or deionized water or another aqueous-based
solution under suitable conditions of time and temperature.
At this stage, another intermediate article has been created, which
intermediate article comprises a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
the exposed regions of the polymeric layer comprising a pattern of
an electroless seed metal compound (comprising a non-reducing
reagent as described above) and a crosslinked polymer derived from
the reactive polymer in the reactive composition described above,
wherein the electroless seed metal compound has a pK.sub.sp of less
than 40, and
the non-exposed regions comprise substantially no reactive
composition.
This intermediate article can be immediately immersed in an
aqueous-based electroless metal plating bath or solution, or the
intermediate article can be stored with just the catalytic pattern
comprising electroless seed metal compound for use at a later
time.
The intermediate article can be contacted with an electroless
plating metal that is the same as or different from the metal
within the electroless seed metal compound using the aqueous-based
solutions and conditions described above. In most embodiments, the
electroless plating metal is a different metal from the metal
within the electroless seed metal compound.
After the electroless plating procedure, the product article is
removed from the aqueous-based electroless plating bath or solution
and can again be washed using distilled water or deionized water or
another aqueous-based solution to remove any residual electroless
plating chemistry. At this point, the polymeric layer and
electrolessly plated metal are generally stable and can be used for
their intended purpose.
Thus, this method provides a product article comprising a substrate
and having disposed thereon a polymeric layer comprising exposed
regions and non-exposed regions,
the exposed regions comprising a pattern of an electroless seed
metal compound (comprising a non-reducing reagent as described
above) which has been electrolessly plated with the same or
different metal that is part of the electroless seed metal compound
within a crosslinked polymer derived from the reactive polymer in
the reactive composition described above, and
the non-exposed regions comprising substantially no reactive
composition.
The present invention provides at least the following embodiments
and combinations thereof, but other combinations of features are
considered to be within the present invention as a skilled artisan
would appreciate from the teaching of this disclosure:
1. A method for forming a pattern in a polymeric layer, the method
comprising:
providing a polymeric layer comprising a reactive composition that
comprises: (1) a reactive polymer that is metal ion-complexing,
water-soluble, and crosslinkable, which reactive polymer comprises
pendant groups comprising crosslinkable
--C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R and R.sup.1 are
independently hydrogen or an alkyl group having 1 to 6 carbon
atoms, a 5- to 6-membered cycloalkyl group, an alkoxy group having
1 to 6 carbon atoms, a phenyl group, or a phenoxy group, and Y is a
substituted or unsubstituted aryl or aromatic heterocyclic ring,
and (2) optionally, a photosensitizer,
patternwise exposing the polymeric layer to radiation having a
.lamda..sub.max of at least 150 nm that is sufficient to induce
crosslinking within the reactive polymer, to provide a polymeric
layer comprising non-exposed regions and exposed regions comprising
an at least partially crosslinked polymer derived from the reactive
polymer,
optionally heating the polymeric layer simultaneously with or after
patternwise exposing the polymeric layer but before removing the
reactive composition comprising the reactive polymer in the
non-exposed regions, at a temperature sufficient to further
crosslink the at least partially crosslinked polymer in the exposed
regions of the polymeric layer,
removing the reactive composition comprising the reactive polymer
in the non-exposed regions,
contacting the exposed regions of the polymeric layer with
electroless seed metal ions to form a pattern of electroless seed
metal ions in the exposed regions of the polymeric layer,
reducing the pattern of electroless seed metal ions to provide a
pattern of corresponding electroless seed metal nuclei in the
exposed regions of the polymeric layer, and
electrolessly plating the corresponding electroless seed metal
nuclei in the exposed regions of the polymeric layer with a metal
that is the same as or different from the corresponding electroless
seed metal nuclei.
2. The method of embodiment 1, wherein the reactive composition
further comprises a photosensitizer in the polymeric layer in an
amount of at least 0.1 weight % based on the total solids in the
polymeric layer, which photosensitizer provides sensitization at a
.lamda..sub.max of at least 150 nm and up to and including 700
nm.
3. The method of embodiment 1 or 2, further comprising:
heating the polymeric layer after patternwise exposing the
polymeric layer but before removing the reactive composition
comprising the reactive polymer in the non-exposed regions, at a
temperature sufficient to further crosslink the at least partially
crosslinked polymer in the exposed regions of the polymeric
layer.
4. The method of any of embodiments 1 to 3, comprising contacting
the exposed regions in the polymeric layer with electroless seed
metal ions selected from the groups consisting of silver ions,
platinum ions, palladium ions, gold ions, rhodium ions, nickel
ions, iridium ions, tin ions, and copper ions.
5. The method of any of embodiments 1 to 4, comprising
electrolessly plating with a metal that is selected from the group
consisting of copper(II), silver(I), gold(IV), palladium(II),
platinum(II), nickel(II), chromium(II), and combinations
thereof.
6. The method of any of embodiments 1 to 5, comprising patternwise
exposing the polymeric layer to radiation having a .lamda..sub.max
of at least 150 nm and up to and including 450 nm.
7. The method of any of embodiments 1 to 6, comprising reducing the
electroless seed metal ions in the exposed regions of the polymeric
layer with a reducing agent that is a borane, aldehyde,
hydroquinone, or sugar reducing agent.
8. A precursor article prepared carrying out any of embodiments 1
to 7, the precursor article comprising a substrate and having
disposed thereon a polymeric layer comprising a reactive
composition that comprises:
(1) a reactive polymer that is metal ion-complexing, water-soluble,
and crosslinkable, which reactive polymer comprises pendant groups
comprising crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups
wherein R and R.sup.1 are independently hydrogen or an alkyl group
having 1 to 6 carbon atoms, a 5- to 6-membered cycloalkyl group, an
alkoxy group having 1 to 6 carbon atoms, a phenyl group, or a
phenoxy group, and Y is a substituted or unsubstituted aryl or
aromatic heterocyclic ring, and (2) optionally, a
photosensitizer.
9. An intermediate article obtained during the practice of any of
embodiments 1 to 7, the intermediate article comprising a substrate
and having disposed thereon a polymeric layer comprising exposed
regions and non-exposed regions,
the exposed regions comprising a pattern of at least partially
crosslinked polymer that has been derived from a reactive polymer
that is metal ion-complexing, water-soluble, and crosslinkable,
which reactive polymer comprises pendant groups comprising
crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R
and R.sup.1 are independently hydrogen or an alkyl group having 1
to 6 carbon atoms, a 5- to 6-membered cycloalkyl group, an alkoxy
group having 1 to 6 carbon atoms, a phenyl group, or a phenoxy
group, and Y is a substituted or unsubstituted aryl or aromatic
heterocyclic ring, and
the non-exposed regions comprising a reactive composition that
comprises the reactive polymer that is metal ion-complexing,
water-soluble, and crosslinkable, and optionally, a
photosensitizer.
10. An intermediate article obtained during the practice of any of
embodiments 1 to 7, the intermediate article comprising a substrate
and having disposed thereon a polymeric layer comprising exposed
regions and non-exposed regions,
the exposed regions comprising a pattern of at least partially
crosslinked polymer that has been derived from a reactive polymer
that is metal ion-complexing, water-soluble, and crosslinkable,
which reactive polymer comprises pendant groups comprising
crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R
and R.sup.1 are independently hydrogen or an alkyl group having 1
to 6 carbon atoms, a 5- to 6-membered cycloalkyl group, an alkoxy
group having 1 to 6 carbon atoms, a phenyl group, or a phenoxy
group, and Y is a substituted or unsubstituted aryl or aromatic
heterocyclic ring, and
the non-exposed regions comprising none of the reactive polymer
that is metal ion-complexing, water-soluble, and crosslinkable.
11. An intermediate article obtained during the practice of any of
embodiments 1 to 7, the intermediate article comprising a substrate
and having disposed thereon a polymeric layer comprising exposed
regions and non-exposed regions,
the exposed regions comprising a pattern of electroless seed metal
ions complexed within an at least partially crosslinked polymer
that has been derived from a reactive polymer that is metal
ion-complexing, water-soluble, and crosslinkable, which reactive
polymer comprises pendant groups comprising crosslinkable
--C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R and R.sup.1 are
independently hydrogen or an alkyl group having 1 to 6 carbon
atoms, a 5- to 6-membered cycloalkyl group, an alkoxy group having
1 to 6 carbon atoms, a phenyl group, or a phenoxy group, and Y is a
substituted or unsubstituted aryl or aromatic heterocyclic ring,
and
the non-exposed regions comprising none of the electroless seed
metal ions or the reactive polymer that is metal ion-complexing,
water-soluble, and crosslinkable.
12. An intermediate article obtained during the practice of any of
embodiments 1 to 7, the intermediate article comprising a substrate
and having disposed thereon a polymeric layer comprising exposed
regions and non-exposed regions,
the exposed regions comprising a pattern of electroless seed metal
nuclei complexed within an at least partially crosslinked polymer
that has been derived from a reactive polymer that is metal
ion-complexing, water-soluble, and crosslinkable, which reactive
polymer comprises pendant groups comprising crosslinkable
--C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups wherein R and R.sup.1 are
independently hydrogen or an alkyl group having 1 to 6 carbon
atoms, a 5- to 6-membered cycloalkyl group, an alkoxy group having
1 to 6 carbon atoms, a phenyl group, or a phenoxy group, and Y is a
substituted or unsubstituted aryl or aromatic heterocyclic ring,
and
the non-exposed regions comprising none of the electroless seed
metal nuclei or the reactive polymer that is metal ion-complexing,
water-soluble, and crosslinkable.
13. A product article obtained during the practice of any of
embodiments 1 to 7, the product article comprising a substrate and
having disposed thereon a polymeric layer comprising exposed
regions and non-exposed regions,
the exposed regions comprising a pattern of electrolessly plated
metal complexed within or deposited on the surface of an at least
partially crosslinked polymer that has been derived from a reactive
polymer that is metal ion-complexing, water-soluble, and
crosslinkable, which reactive polymer comprises pendant groups
comprising crosslinkable --C(.dbd.O)--CR.dbd.CR.sup.1--Y-- groups
wherein R and R.sup.1 are independently hydrogen or an alkyl group
having 1 to 6 carbon atoms, a 5- to 6-membered cycloalkyl group, an
alkoxy group having 1 to 6 carbon atoms, a phenyl group, or a
phenoxy group, and Y is a substituted or unsubstituted aryl or
aromatic heterocyclic ring, and
the non-exposed regions comprising none of the electrolessly plated
metal or the reactive polymer that is metal ion-complexing,
water-soluble, and crosslinkable.
14. Any of embodiments 1 to 13, wherein the reactive polymer
comprises a backbone and arranged in any order along the
backbone:
--A-- recurring units comprising the crosslinkable
--C(.dbd.O)--CR--CR.sup.1--Y groups, and --B-- recurring units
comprising pendant metal ion-complexing and water-solubilizing
groups,
wherein the --A-- recurring units are present in an amount of at
least 2 mol % and up to and including 50 mol %, and the --B--
recurring units are present in an amount of at least 50 mol % and
up to and including 98 mol %, both based on the total recurring
units in the reactive polymer.
15. Embodiment 14, wherein the --B-- recurring units comprise
pendant carboxylic acid, carboxylate, sulfonic acid, or sulfonate
groups.
16. Embodiment 14 of 15, wherein the reactive polymer comprises at
least 10 mol % and up to and including 40 mol % of --A-- recurring
units comprising the crosslinkable
--C(.dbd.O)--CR.dbd.CR.sup.1-phenyl groups wherein R and R.sup.1
are independently hydrogen or a methyl, ethyl, or phenyl group,
based on the total recurring units in the reactive polymer, and at
least 60 mol % and up to and including 90 mol % of --B-- recurring
units.
17. Any of embodiments 14 to 16, wherein the reactive polymer
further comprises one or more additional --C-- recurring units that
are different from all --A-- and --B-- recurring units, the one or
more additional --C-- recurring units being present in an amount of
up to and including 20 mol % based on the total reactive polymer
recurring units.
18. Any of embodiments 1 to 17, wherein the reactive polymer is
present in an amount of at least 50 weight % and up to 100 weight %
of the total dry weight of the polymeric layer.
Preparation of 2-Cinnamoylethyl Methacrylate Monomer
Into a 250 ml, 3 neck round bottom flask equipped with a condenser
and magnetic stirring bar, were added 2-hydroxyethyl methacrylate,
(11.30 g, 0.0868 mole) (Mw=130.14 g/mole), toluene (60 g), and
triethylamine (Mw=101.19 g/mole) (8.50 g, 0.084 mole). The
resulting homogenous solution was stirred and lowered into a
pre-heated oil bath set at 55.degree. C. A solution of cinnamoyl
chloride (Mw=166.6 g/mole) (13.33 g, 0.080 mole) dissolved in
toluene (30 g) was slowly added dropwise over 156 minutes. After
this addition, the reaction mixture was stirred for 1 hour, cooled,
removed from the oil bath, and the amine hydrochloride precipitate
that was formed during the reaction was filtered off. The filtered
solution was washed twice with sodium bicarbonate, washed twice
with distilled water, washed twice with dilute hydrochloric acid
solution, and then washed twice with distilled water. It was then
placed over magnesium sulfate for 30 minutes and filtered. The
toluene was rotovaporated off and placed under high vacuum at room
temperature overnight to remove any residual toluene. The final
product was a clear oil with a yellow tint with a Mw=260.29 g/mole
and purity was confirmed by NMR.
Preparation of Polymer A: Copolymer Derived from Methacrylic Acid
and 2-Cinnamoylethyl Methacrylate in a 90:10 Nominal Molar
Ratio
The 2-cinnamoylethyl methacrylate monomer was prepared by reacting
2-hydroxyethyl methacrylate with cinnamoyl chloride in the presence
of triethylamine to neutralize the hydrochloric acid byproduct
using known conditions and starting materials.
Polymer A was prepared using a mixture of 90 mol % methacrylic acid
and 10 mol % 2-cinnamoylethyl methacrylate dissolved in toluene
using 2,2'-azodi(2-methylbutyronitrile) (AMBN) as the
polymerization initiator. The reaction mixture was heated at
65.degree. C. for 18 hours. The resulting reactive polymer was
extracted into water containing sodium hydroxide at a molar
equivalent to the amount of methacrylic acid monomer put into the
reaction. A 6.3 weight % aqueous polymer solution was obtained with
the resulting Polymer A that was determined to have a weight
average molecular weight of about 850,000 by size exclusion
chromatography.
Preparation of Polymer B: Alternative Preparation of Copolymer
Derived from Methacrylic Acid and 2-Cinnamoylethyl Methacrylate in
a 90:10 Nominal Molar Ratio
The following were placed into a 100 ml, single neck round bottom
flask: methacrylic acid (2.34 g, 0.02718 mole), 2-cinnamoylethyl
methacrylate monomer (0.78 g, 0.00299 mole),
2,2'-azobis(2-methylbutyronitrile) AMBN initiator (0.03 g, 1 weight
% based on total solids), and methyl ethyl ketone (MEK)/isopropyl
alcohol (IPA) at a 50/50 volume ratio (12.48 g, 20% solids). The
reaction mixture was purged with nitrogen for 30 minutes and then
placed in a pre-heated oil bath set at 75.degree. C. for 16 hours
while stirring with a magnetic stirring bar. The cooled reaction
solution was then precipitated into acetone and the precipitate was
washed several times with acetone with the resulting white solid
material placed in a 40.degree. C. vacuum oven overnight. The solid
material was then weighed (2.80 g, 90% yield) and the product was
neutralized with enough 2 weight % sodium hydroxide solution to
neutralize 50% of the methacrylic acid and the final solution was
delivered at 5% solids. The weight average molecular weight of the
resulting Polymer B was determined to be 182,000 by size exclusion
chromatography.
Preparation of Polymer C: Copolymer Derived from Methacrylic Acid
and 2-Cinnamoyl-Ethyl Methacrylate in an 80:20 Nominal Molar
Ratio
This preparation was identical to that used to prepare Copolymer B
except that the monomer nominal molar ratio was adjusted to give a
polymer containing 20 mol % of recurring units derived from
2-cinnamoylethyl methacrylate. The weight average molecular weight
of the resulting Polymer C was determined to be 130,000 by size
exclusion chromatography.
Preparation of Polymer D: Copolymer Derived from Methacrylic Acid
and 2-Cinnamoyl-Ethyl Methacrylate in a 70:30 Nominal Molar
Ratio
This preparation was identical to that used to prepare Polymer B
except that the monomer nominal molar ratio was adjusted to give a
polymer containing 30 mol % of recurring units derived from
2-cinnamoylethyl methacrylate. The methacrylic acid was neutralized
at 100% with 2% sodium hydroxide. The weight average molecular
weight of the resulting Polymer D was determined to be 81,900 by
size exclusion chromatography.
Preparation of Polymer E: Copolymer Derived from Methacrylic Acid
and 2-Cinnamoyl-Ethyl Methacrylate in a 60:40 Nominal Molar
Ratio
This preparation was identical to that used to prepare Polymer B
except that the monomer nominal molar ratio was adjusted to give a
polymer containing 40 mol % of recurring units derived from
2-cinnamoylethyl methacrylate. The methacrylic acid was neutralized
at 100% with 2% sodium hydroxide. The weight average molecular
weight of the resulting Polymer E was determined to be 61,800 by
size exclusion chromatography.
Preparation of Polymer F: Copolymer Derived from Methacrylic Acid
and 2-Cinnamoyl-Ethyl Methacrylate in a 50:50 Nominal Molar
Ratio
This preparation was identical to that used to prepare Polymer B
except that the monomer nominal molar ratio was adjusted to give a
polymer containing 50 mol % of recurring units derived from
2-cinnamoylethyl methacrylate. The methacrylic acid was neutralized
at 100% with 2% sodium hydroxide. The weight average molecular
weight of the resulting Polymer F was determined to be 87,900 by
size exclusion chromatography.
Preparation of Polymer G: Terpolymer Derived from Methacrylic Acid,
2-Cinnamoyl-Ethyl Methacrylate, and Butyl Methacrylate in a
70:20:10 Nominal Molar Ratio
The following materials were put into a 100 ml, single neck round
bottom flask: methacrylic acid (2.05 g, 0.0238 mole),
2-cinnamoylethyl methacrylate monomer (1.77 g, 0.0068 mole), butyl
methacrylate (0.48 g, 0.0034 mole)
2,2'-azobis(2-methylbutyronitrile) AMBN initiator (0.043 g, 1
weight % based on total solids), and MEK/IPA at a 50/50 volume
ratio (17.2 g, 20% solids). The reaction solution was purged with
nitrogen for 30 minutes and then placed in a pre-heated oil bath
set at 75.degree. C. for 16 hours with stirring using a magnetic
stirring bar. The cooled solution was then precipitated into
heptane and the precipitate was washed several times with heptane
with the resulting white solid material placed in a 50.degree. C.
vacuum oven overnight. The solid was then weighed (3.40 g, 79%
yield), the product was neutralized with enough 2% sodium hydroxide
solution to neutralize 100% of the methacrylic acid, and the final
solution was delivered at 5% solids
Preparation of the Electroless Copper(II) Plating Bath
The following components were dissolved inside a glass container
that had been pre-cleaned with concentrated nitric acid followed by
a thorough rinse with distilled water to eliminate any trace of
metal on the glass: 1.8 g of copper(II) sulfate pentahydrate, 6.25
g of tetrasodium EDTA (ethylenediaminetetraacetic acid)
tetrahydrate, 0.005 g of potassium ferrocyanide trihydrate, 2.25 g
of a 37 weight % formaldehyde solution, 80 g of distilled water,
and 2 to 3 g of a 45 weight % sodium hydroxide solution to adjust
the aqueous-based solution pH to 12.8.
Preparation of the Electroless Nickel(II) Plating Bath
The following components were dissolved inside a glass contained
that was pre-cleaned with concentrated nitric acid followed by a
thorough rinse with distilled water to eliminate any trace of metal
on the glass. 0.36 g of nickel(II) sulfate hexahydrate, 3.37 g of
an 85% lactic acid solution, 1.42 g of glacial acetic acid, 0.26 g
of propionic acid, 0.25 ppm of thiourea in a 100 ppm methanol
solution, 2.835 g of a 14 molar ammonium hydroxide, 78.24 g of
distilled water, and about 1.8 g of sodium hypophosphite partial
hydrate (assume 95% anhydrous) added immediately before use.
Invention Example 1
Forming Conductive Conner Pattern
A 6.3 weight % aqueous reactive composition obtained from the
reactive Polymer A preparation described above was diluted with
water to 5 weight % polymer and spin coated as a reactive
composition at 4000 RPM onto a PET [poly(ethylene terephthalate)]
film substrate having a polymeric adhesion layer of a copolymer
derived from glycidyl methacrylate and butyl acrylate that had been
applied before stretching the PET film, to provide a polymeric
layer on precursor articles.
Each precursor article was imagewise exposed to broadband
ultraviolet light through a chrome-on-quartz contact mask for 240
seconds. Some exposed precursor articles were left at room
temperature for about 24 hours while other exposed precursor
articles were immediately contacted with a vacuum hot plate at
120.degree. C. for 60 seconds (heating procedure).
Following this treatment at either room temperature or on the
hotplate, the exposed precursors were then immersed in well
agitated distilled water for up to 10 minutes to wash off the
reactive composition in the non-exposed regions. Some of the
resulting intermediate articles were then allowed to air dry while
intermediate articles were immediately immersed in the silver
nitrate bath described below.
All washed intermediate articles, whether air-dried or not were
immersed within an aqueous-based 0.4 molar silver nitrate solution
containing electroless seed silver ions for 2 minutes, rinsed in
distilled water, and then immersed in a 1 weight % aqueous-based
dimethylamine borane (DMAB) reducing bath for 1 minute, followed by
a distilled water rinse.
These resulting intermediate articles were then immersed in the
electroless copper(II) plating bath described above for 5 minutes.
A brilliant continuous copper film was formed in all UV-exposed
regions of the polymeric layers on the substrate. In the resulting
copper pattern, line widths of 5 to 6 .mu.m diameter were
faithfully reproduced and exhibited high conductivity.
Invention Examples 2-6
Use of Various Reactive Polymers
Precursor articles were prepared using reactive Polymers C, D, E,
F, and G in the reactive composition and by spin coating 5 weight %
of each reactive polymer preparation containing 0.1 weight % of
Dupont Capstone FS-35 surfactant onto the PET substrate as
described in Invention Example 1. Each precursor article containing
the respective polymeric layer was imagewise exposed using a 1000
watt UV light source filtered through a 350 nm to 450 nm bandpass
dichroic mirror for a time series of 8 to 60 seconds. Each exposed
polymeric layer was then heated to 60.degree. C. for 1 minute,
washed with agitated distilled water for 2 minutes to remove the
non-exposed reactive composition, immersed in a 0.4 molar silver
nitrate bath for 1 minute, rinsed in distilled water, immersed in a
1 weight % aqueous-based dimethylamine borane (DMAB) reducing bath
for 30 seconds, rinsed again with distilled water, and immersed in
the electroless copper(II) plating bath described above for 6
minutes followed by a final rinse and air drying.
Conductive copper patterns were formed in each product article
using each of the reactive polymers. Reactive polymers containing
higher levels of recurring units containing crosslinkable cinnamoyl
groups (embodiments of the --A-- recurring units defined herein)
inhibited copper plating at long exposure times but desirable
conductive patterns with shorter exposure times.
Invention Example 7
Forming Nickel Conductive Pattern
A precursor article was prepared using reactive Polymer C and
imagewise exposed to UV radiation as described in Invention Example
2. Non-exposed reactive composition (non-exposed regions) was then
removed from the substrate using agitated distilled water as
described above in Invention Example 2.
The resulting intermediate article was then immersed within a 50:50
water:acetonitrile solution of 0.001 molar palladium chloride
containing electroless palladium seed ions for 10 minutes and
rinsed with distilled water. The palladium ions within the exposed
regions in the polymeric layer were then contacted with a 1 weight
% aqueous-based dimethylamine borane (DMAB) reducing bath for 5
minutes, rinsed with distilled water, and contacted with the
electroless nickel(II) plating bath described above for 10 minutes
at 55.degree. C. A conductive nickel metal pattern was formed in
the exposed regions of the resulting product article.
Invention Examples 8 & 9
Use of Reactive Composition with and without Water-Insoluble
Photosensitizer
For Invention Example 8, a reactive composition formulation was
prepared containing 4.75 weight % of Polymer C, 0.05 weight % of
Dupont Capstone FS-35 surfactant, and 0.043 weight % of
2-[bis(2-furoyl)methylene]-1-methylnaphtho[1,2-d]thiazoline (BFT
photosensitizer) added from a 2 weight % solution in
.gamma.-butyrolactone. This photosensitizer formed a fine
dispersion in the aqueous formulation upon thorough mixing. The
reactive composition formulation was spin coated at 1000 RPM onto a
PET [poly(ethylene terephthalate)] film substrate having a
polymeric adhesion layer of a copolymer derived from glycidyl
methacrylate and butyl acrylate that had been applied before
stretching the PET film, to provide a polymeric layer on the
substrate in a resulting precursor article.
The precursor article was imagewise exposed to 350 nm to 450 nm
ultraviolet light through a chrome-on-quartz contact mask for 15
seconds. The exposed precursor was then baked at 60.degree. C. for
60 seconds. The exposed and baked intermediate article was then
immersed in well agitated distilled water for 2 minute 2 to wash
off the reactive composition comprising the reactive polymers in
the non-exposed regions. The washed intermediate article was then
immersed within an aqueous-based 0.4 molar silver nitrate solution
containing electroless seed silver ions for 1 minute, rinsed in
distilled water, immersed in a 1 weight % aqueous-based
dimethylamine borane (DMAB) reducing bath for 30 seconds, and then
followed by a another distilled water rinse.
These resulting intermediate article was then immersed in the
electroless copper(II) plating bath described above for 6 minutes.
A brilliant continuous copper film was formed in all UV-exposed
regions of the polymeric layer on the substrate in the resulting
product article. In the resulting copper pattern, line widths of 5
to 6 .mu.m diameter were faithfully reproduced and exhibited high
conductivity.
Another precursor article was similarly prepared for Invention
Example 9 except that the BFT photosensitizer was omitted. The
resulting product article contained fine copper lines that
represented poorer reproductions of the desired image at the 60
second exposure level. Such precursor article could likely be
improved using an optimized reactive polymer or different exposure
or treatment conditions.
Invention Examples 10 & 11
Use of Reactive Composition with Water-Soluble Photosensitizer
For Invention Example 10, a reactive composition formulation was
prepared containing 4.25 weight % of Polymer C, 0.05 weight % of
Dupont Capstone FS-35 surfactant, and 0.043 weight % of pyridinium,
3-((7-methoxy-2-oxo-2H-1-benzopyran-3-yl)carbonyl)-1-methyl,
fluorosulfate as the photosensitizer. The reactive composition
formulation was spin coated at 1000 RPM onto a PET [poly(ethylene
terephthalate)] film substrate having a polymeric adhesion layer of
a copolymer derived from glycidyl methacrylate and butyl acrylate
that had been applied before stretching the PET film, to provide a
polymeric layer on the substrate in a resulting precursor
article.
The precursor article was imagewise exposed to 350 nm to 450 nm
ultraviolet light through a chrome-on-quartz contact mask for 30
seconds and then baked at 60.degree. C. for 60 seconds. The exposed
and baked intermediate article was then immersed in well agitated
distilled water for 2 minutes to wash off the reactive composition
comprising the reactive polymer in the non-exposed regions. The
washed intermediate article was then immersed within an
aqueous-based 0.4 molar silver nitrate solution containing
electroless seed silver ions for 1 minute, rinsed in distilled
water, immersed in a 1 weight % aqueous-based dimethylamine borane
(DMAB) reducing bath for 30 seconds, and followed by another
distilled water rinse.
The resulting intermediate article was then immersed in the
electroless copper(II) plating bath described above for 5 minutes.
A brilliant continuous copper film was formed in all UV-exposed
regions of the polymeric layer on the substrate in the product
article. In the resulting copper pattern, line widths of 5 to 6
.mu.m diameter were faithfully reproduced and exhibited high
conductivity.
A precursor article was similarly prepared for Invention Example 11
except that the water soluble photosensitizer was omitted from the
reactive composition. The resulting product article exhibited
poorer copper line reproduction and lower conductivity at the 30
second exposure level. Such precursor article could likely be
improved using optimized reactive polymer or different exposure or
treatment conditions.
The invention has been described in detail with particular
reference to certain preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *